🕷️ Crawler Inspector

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Raw Queries and Responses

1. Shard Calculation

Query:

Response:

Calculated Shard: 84 (from laksa155)

2. Crawled Status Check

Query:

curl -X POST \
  'http://laksa084.int.ahrefs:8124/' \
  -H 'Content-Type: text/plain' \
  -H 'X-ClickHouse-Database: crawler3' \
  -H 'Authorization: Basic YXBpOg==' \
  -d 'SELECT getAhrefsURLFromUnparsed(src_unparsed) AS found_url, ifNull(toUnixTimestamp(download_stamp), 0) AS crawl_time, ifNull(toUnixTimestamp(props_url_first_seen), 0) AS first_indexed_time, download_http_code AS http_code, src_unparsed AS src_unparsed, src_root_hash AS src_root_hash, history_drop_reason AS history_drop_reason, meta_title AS meta_title, meta_descriptions AS meta_descriptions, attrs_boilerpipe_text AS attrs_boilerpipe_text, attrs_markdown AS attrs_markdown, attrs_readable_markdown AS attrs_readable_markdown, meta_canonical AS meta_canonical FROM crawler3.page_info_local FINAL PREWHERE (src_root_hash, src_unparsed) IN ((getAhrefsRootHashFromUnparsed(getAhrefsUnparsedNoserviceFromURL(\'https://www.nytimes.com/interactive/2020/health/sinovac-covid-19-vaccine.html\')), getAhrefsUnparsedNoserviceFromURL(\'https://www.nytimes.com/interactive/2020/health/sinovac-covid-19-vaccine.html\'))) FORMAT JSONEachRow'

Response:

{"found_url":"https:\/\/www.nytimes.com\/interactive\/2020\/health\/sinovac-covid-19-vaccine.html","crawl_time":1773168638,"first_indexed_time":1608819463,"http_code":200,"src_unparsed":"com,nytimes!www,\/interactive\/2020\/health\/sinovac-covid-19-vaccine.html s443","src_root_hash":"4566504020376537684","history_drop_reason":null,"meta_title":"How the Sinovac Covid-19 Vaccine Works - The New York Times","meta_descriptions":["Using inactivated coronaviruses to train the immune system."],"attrs_boilerpipe_text":"U.S.A.\nClose nav\nWorld\nClose nav\nHealth\nClose nav\nThe private Chinese company Sinovac developed a\ncoronavirus vaccine\ncalled\nCoronaVac\n. The vaccine is approved for use in China and authorized for emergency use in more than a dozen other countries. In a trial in Brazil, researchers found it had an efficacy against infections with or without symptoms of\n50.65 percent\n. In a trial in Turkey, researchers found it had an efficacy of 91.25 percent against Covid-19 infections with symptoms.\nA Vaccine Made From Coronaviruses\nCoronaVac works by teaching the immune system to make antibodies against the SARS-CoV-2 coronavirus. The antibodies attach to viral proteins, such as the so-called spike proteins that\nstud its surface\n.\nTo create CoronaVac, the Sinovac researchers started by obtaining samples of the coronavirus from patients in China, Britain, Italy, Spain and Switzerland. One sample from China eventually served as the basis for the vaccine.\nKilling the Virus\nThe researchers grew large stocks of the coronavirus in monkey kidney cells. Then they doused the viruses with a chemical called beta-propiolactone. The compound disabled the coronaviruses by bonding to their genes. The inactivated coronaviruses could no longer replicate. But their proteins, including spike, remained intact.\nThe researchers then drew off the inactivated viruses and mixed them with a tiny amount of an aluminum-based compound called an adjuvant. Adjuvants stimulate the immune system to boost its response to a vaccine.\nInactivated viruses have been used for over a century. Jonas Salk used them to create his\npolio vaccine\nin the 1950s, and they’re the bases for vaccines against other diseases including\nrabies\nand\nhepatitis A\n.\nPrompting an Immune Response\nBecause the coronaviruses in CoronaVac are dead, they can be injected into the arm without causing Covid-19. Once inside the body, some of the inactivated viruses are swallowed up by a type of immune cell called an antigen-presenting cell.\nThe antigen-presenting cell tears the coronavirus apart and displays some of its fragments on its surface. A so-called helper T cell may detect the fragment. If the fragment fits into one of its surface proteins, the T cell becomes activated and can help recruit other immune cells to respond to the vaccine.\nMaking Antibodies\nAnother type of immune cell, called a B cell, may also encounter the inactivated coronavirus. B cells have surface proteins in a huge variety of shapes, and a few might have the right shape to latch onto the coronavirus. When a B cell locks on, it can pull part or all of the virus inside and present coronavirus fragments on its surface.\nA helper T cell activated against the coronavirus can latch onto the same fragment. When that happens, the B cell gets activated, too. It proliferates and pours out antibodies that have the same shape as their surface proteins.\nStopping the Virus\nOnce vaccinated with CoronaVac, the immune system can respond to an infection of live coronaviruses. B cells produce antibodies that stick to the invaders. Antibodies that target the spike protein can prevent the virus from entering cells. Other kinds of antibodies may block the virus by other means.\nRemembering the Virus\nWhile CoronaVac can offer some protection against Covid-19, no one can yet say how long that protection lasts. It’s possible that the level of antibodies drops over the course of months. But the immune system also contains special cells called memory B cells that might retain information about the coronavirus for years or even decades.\nVaccine Timeline\nJanuary, 2020\nSinovac begins developing an inactivated vaccine against the coronavirus.\nSinovac engineers working with monkey kidney cells.\nNicolas Asfouri\/Agence France-Presse\nJune\nPhase 1\/2 trials on 743 volunteers find\nno severe adverse effects\n.\nJuly\nSinovac launches a Phase 3 trial in Brazil, followed by others in\nIndonesia\nand\nTurkey\n. Reuters\nreports\nthat the Chinese government gave the Sinovac vaccine emergency approval for limited use.\nA dose of CoronaVac in Turkey.\nEmrah Gurel\/Associated Press\nOctober\nAuthorities in the eastern Chinese city of Jiaxing announce they are\ngiving CoronaVac\nto people in relatively high-risk jobs, including medical workers, port inspectors and public service personnel.\nOct. 19\nOfficials in Brazil\nsay\nthat Sinovac is the safest of five vaccines they are testing in Phase 3 trials.\nNovember\nSinovac\npublishes\nthe details of its Phase 1\/2 trial in a medical journal, showing a comparatively modest production of antibodies. Only a Phase 3 trial will demonstrate if that is enough to protect people from Covid-19.\nNov. 19\nThe Brazilian government\nannounces\nthat they paused the country’s Sinovac trial the previous month because of an adverse event. The details of the pause were murky, raising suspicions that politics were involved. Two days after the announcement, the trial was\nallowed to resume\n. The Brazilian trial has recorded enough cases of Covid-19 to let researchers determine Sinovac’s efficacy. They expect to release their results by Dec. 23.\nOfficials in Brazil hold boxes from a shipment of the vaccine.\nAlexandre Schneider\/Getty Images\nDecember\nSinovac\nsays\nit expects to manufacture 300 million doses in 2020 and increase capacity to an annual production of 600 million doses.\nDec. 23\nBrazilian researchers announce that CoronaVac has an efficacy of\nover 50 percent\n.\nDec. 24\nTurkish officials announce that the vaccine has an efficacy rate of\n91.25 percent\n.\nJan. 7, 2021\nResearchers in Brazil\nannounce\nthat CoronaVac has an efficacy of 78 percent. None of the vaccinated volunteers in their Phase 3 trial developed severe or moderate cases of Covid-19. But the efficacy estimate was based on the vaccine’s performance in a subgroup of volunteers. The overall efficacy is not formally released.\nJan. 11\nIndonesia\nauthorizes the vaccine for emergency use.\nJan. 13\nResearchers in Brazil\nannounce\nthat CoronaVac has an overall efficacy of just over 50 percent. Turkey authorizes the vaccine for emergency use.\nFeb. 6\nSinovac announces that China has given CoronaVac\nconditional approval\n.\nMarch 13\nChina asks visa applicants to get\ninoculated with Chinese-made coronavirus vaccines\n.\nApril 1\nSinovac\nannounces\nthat its capacity has increased to 2 billion doses after completing a third production line.\nSources: National Center for Biotechnology Information; Science; The Lancet; Lynda Coughlan, University of Maryland School of Medicine; Jenna Guthmiller, University of Chicago.\nTracking the Coronavirus","attrs_markdown":"[Skip to content](https:\/\/www.nytimes.com\/interactive\/2020\/health\/sinovac-covid-19-vaccine.html#site-content)[Skip to site index](https:\/\/www.nytimes.com\/interactive\/2020\/health\/sinovac-covid-19-vaccine.html#site-index)\n\nSearch & Section Navigation\n\nSection Navigation\n\nSearch\n\n[Health](https:\/\/www.nytimes.com\/section\/health)\n\n[Log in](https:\/\/myaccount.nytimes.com\/auth\/login?response_type=cookie&client_id=vi&redirect_uri=https%3A%2F%2Fwww.nytimes.com%2Fsubscription%2Fonboarding-offer%3FcampaignId%3D7JFJX%26EXIT_URI%3Dhttps%253A%252F%252Fwww.nytimes.com%252Finteractive%252F2020%252Fhealth%252Fsinovac-covid-19-vaccine.html&asset=masthead)\n\n[Today’s Paper](https:\/\/www.nytimes.com\/section\/todayspaper)\n\n[Health](https:\/\/www.nytimes.com\/section\/health)\\|How the Sinovac Vaccine Works\n\nhttps:\/\/nyti.ms\/38xfqoT\n\n- Share full article\n- 0\n\n# How the Sinovac Vaccine Works\nBy [Jonathan Corum](https:\/\/www.nytimes.com\/by\/jonathan-corum) and [Carl Zimmer](https:\/\/www.nytimes.com\/by\/carl-zimmer)Updated May 7, 2021\n\n[阅读简体中文版](https:\/\/cn.nytimes.com\/health\/20201229\/sinovac-covid-19-vaccine\/ \"Read in Simplified Chinese\")[閱讀繁體中文版](https:\/\/cn.nytimes.com\/health\/20201229\/sinovac-covid-19-vaccine\/zh-hant\/ \"Read in Traditional Chinese\")[Leer en español](https:\/\/www.nytimes.com\/es\/interactive\/2021\/health\/sinovac-vacuna-covid.html \"Read in Spanish\")\n\n- Share full article\n- 0\n\nU.S.A.\n\nClose nav\n\n- [Latest Maps and Data](https:\/\/www.nytimes.com\/interactive\/2021\/us\/covid-cases.html)\n- [Vaccinations by State](https:\/\/www.nytimes.com\/interactive\/2020\/us\/covid-19-vaccine-doses.html)\n- [Your Places](https:\/\/www.nytimes.com\/interactive\/2021\/us\/covid-cases-deaths-tracker.html)\n- [Hospitals](https:\/\/www.nytimes.com\/interactive\/2020\/us\/covid-hospitals-near-you.html)\n\n![Search icon](https:\/\/static01.nyt.com\/newsgraphics\/2021\/coronavirus-tracking\/images\/icon-search.svg)\n\n- [Alabama](https:\/\/www.nytimes.com\/interactive\/2021\/us\/alabama-covid-cases.html)\n- [Alaska](https:\/\/www.nytimes.com\/interactive\/2021\/us\/alaska-covid-cases.html)\n- [Arizona](https:\/\/www.nytimes.com\/interactive\/2021\/us\/arizona-covid-cases.html)\n- 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Data](https:\/\/www.nytimes.com\/interactive\/2021\/world\/covid-cases.html)\n- [Vaccinations by Country](https:\/\/www.nytimes.com\/interactive\/2021\/world\/covid-vaccinations-tracker.html)\n\n- [Australia](https:\/\/www.nytimes.com\/interactive\/2021\/world\/australia-covid-cases.html)\n- [Brazil](https:\/\/www.nytimes.com\/interactive\/2021\/world\/brazil-covid-cases.html)\n- [Canada](https:\/\/www.nytimes.com\/interactive\/2021\/world\/canada-covid-cases.html)\n- [China](https:\/\/www.nytimes.com\/interactive\/2021\/world\/china-covid-cases.html)\n- [France](https:\/\/www.nytimes.com\/interactive\/2021\/world\/france-covid-cases.html)\n- [Germany](https:\/\/www.nytimes.com\/interactive\/2021\/world\/germany-covid-cases.html)\n- [India](https:\/\/www.nytimes.com\/interactive\/2021\/world\/india-covid-cases.html)\n- [Italy](https:\/\/www.nytimes.com\/interactive\/2021\/world\/italy-covid-cases.html)\n- [Japan](https:\/\/www.nytimes.com\/interactive\/2021\/world\/japan-covid-cases.html)\n- [Mexico](https:\/\/www.nytimes.com\/interactive\/2021\/world\/mexico-covid-cases.html)\n- [South Africa](https:\/\/www.nytimes.com\/interactive\/2021\/world\/south-africa-covid-cases.html)\n- [Spain](https:\/\/www.nytimes.com\/interactive\/2021\/world\/spain-covid-cases.html)\n- [United Kingdom](https:\/\/www.nytimes.com\/interactive\/2021\/world\/united-kingdom-covid-cases.html)\n\nHealth\n\nClose nav\n\n- [Vaccine Development](https:\/\/www.nytimes.com\/interactive\/2020\/science\/coronavirus-vaccine-tracker.html)\n- [Coronavirus Variants](https:\/\/www.nytimes.com\/interactive\/2021\/health\/coronavirus-variant-tracker.html)\n- [Treatments](https:\/\/www.nytimes.com\/interactive\/2020\/science\/coronavirus-drugs-treatments.html)\n- [Answers to Your Covid-19 Questions](https:\/\/www.nytimes.com\/interactive\/2020\/world\/coronavirus-tips-advice.html)\n- [How the Covid-19 Vaccines Work](https:\/\/www.nytimes.com\/interactive\/2021\/health\/how-covid-19-vaccines-work.html)\n- [Symptoms of Covid-19](https:\/\/www.nytimes.com\/interactive\/2020\/08\/05\/well\/covid-19-symptoms.html)\n- [What Happens in an Infection](https:\/\/www.nytimes.com\/interactive\/2020\/10\/02\/science\/charting-a-coronavirus-infection.html)\n- [How Masks Work](https:\/\/www.nytimes.com\/interactive\/2020\/10\/30\/science\/wear-mask-covid-particles-ul.html)\n\n![](https:\/\/static01.nyt.com\/newsgraphics\/2020\/12\/05\/how-coronavirus-vaccines-work\/223b8183b7e9cde2b16745b6f17504082c328540\/1-syringe-sinovac-450.png)\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nThe private Chinese company Sinovac developed a [coronavirus vaccine](https:\/\/www.nytimes.com\/interactive\/2020\/science\/coronavirus-vaccine-tracker.html#sinovac) called **CoronaVac**. The vaccine is approved for use in China and authorized for emergency use in more than a dozen other countries. In a trial in Brazil, researchers found it had an efficacy against infections with or without symptoms of [50\\.65 percent](https:\/\/www.nytimes.com\/2021\/01\/13\/business\/chinese-vaccine-brazil-sinovac.html). In a trial in Turkey, researchers found it had an efficacy of 91.25 percent against Covid-19 infections with symptoms.\n\n## A Vaccine Made From Coronaviruses\nCoronaVac works by teaching the immune system to make antibodies against the SARS-CoV-2 coronavirus. The antibodies attach to viral proteins, such as the so-called spike proteins that [stud its surface](https:\/\/www.nytimes.com\/interactive\/2020\/health\/coronavirus-unveiled.html).\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nSpikes\n\nSpike\n\nprotein\n\ngene\n\n![](https:\/\/static01.nyt.com\/newsgraphics\/2020\/12\/05\/how-coronavirus-vaccines-work\/223b8183b7e9cde2b16745b6f17504082c328540\/2-virion-600.png)\n\nSpikes\n\nSpike\n\nprotein\n\ngene\n\nCORONAVIRUS\n\nTo create CoronaVac, the Sinovac researchers started by obtaining samples of the coronavirus from patients in China, Britain, Italy, Spain and Switzerland. One sample from China eventually served as the basis for the vaccine.\n\n## Killing the Virus\nThe researchers grew large stocks of the coronavirus in monkey kidney cells. Then they doused the viruses with a chemical called beta-propiolactone. The compound disabled the coronaviruses by bonding to their genes. The inactivated coronaviruses could no longer replicate. But their proteins, including spike, remained intact.\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nInactivated\n\ngenes\n\nBeta-\n\npropiolactone\n\n![](https:\/\/static01.nyt.com\/newsgraphics\/2020\/12\/05\/how-coronavirus-vaccines-work\/223b8183b7e9cde2b16745b6f17504082c328540\/2-virion-sinovac-600.png)\n\nBeta-\n\npropiolactone\n\nINACTIVATED\n\nCORONAVIRUS\n\nInactivated\n\ngenes\n\nThe researchers then drew off the inactivated viruses and mixed them with a tiny amount of an aluminum-based compound called an adjuvant. Adjuvants stimulate the immune system to boost its response to a vaccine.\n\nInactivated viruses have been used for over a century. Jonas Salk used them to create his [polio vaccine](https:\/\/www.nytimes.com\/1955\/04\/13\/archives\/salk-polio-vaccine-proves-success-millions-will-be-immunized-soon.html) in the 1950s, and they’re the bases for vaccines against other diseases including [rabies](https:\/\/www.nytimes.com\/1973\/08\/21\/archives\/vaccine-for-rabies-developed-cutting-shots-from-14-to-1-vaccine.html) and [hepatitis A](https:\/\/www.nytimes.com\/1992\/08\/13\/us\/test-indicates-new-vaccine-works-against-hepatitis-a.html).\n\n## Prompting an Immune Response\nBecause the coronaviruses in CoronaVac are dead, they can be injected into the arm without causing Covid-19. Once inside the body, some of the inactivated viruses are swallowed up by a type of immune cell called an antigen-presenting cell.\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nEngulfing\n\nthe virus\n\nDigesting\n\nproteins\n\nANTIGEN-\n\nPRESENTING\n\nCELL\n\nPresenting\n\nvirus protein\n\nfragments\n\nHELPER\n\nT CELL\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nINACTIVATED\n\nCORONAVIRUS\n\nEngulfing\n\nthe virus\n\nANTIGEN-\n\nPRESENTING\n\nCELL\n\nDigesting\n\nvirus proteins\n\nPresenting\n\nvirus protein\n\nfragments\n\nHELPER\n\nT CELL\n\n![](https:\/\/static01.nyt.com\/newsgraphics\/2020\/12\/05\/how-coronavirus-vaccines-work\/223b8183b7e9cde2b16745b6f17504082c328540\/5-apc-sinovac-600.png)\n\nINACTIVATED\n\nCORONAVIRUS\n\nEngulfing\n\nthe virus\n\nANTIGEN-\n\nPRESENTING\n\nCELL\n\nDigesting\n\nvirus proteins\n\nPresenting\n\nvirus protein\n\nfragments\n\nHELPER\n\nT CELL\n\nThe antigen-presenting cell tears the coronavirus apart and displays some of its fragments on its surface. A so-called helper T cell may detect the fragment. If the fragment fits into one of its surface proteins, the T cell becomes activated and can help recruit other immune cells to respond to the vaccine.\n\n## Making Antibodies\nAnother type of immune cell, called a B cell, may also encounter the inactivated coronavirus. B cells have surface proteins in a huge variety of shapes, and a few might have the right shape to latch onto the coronavirus. When a B cell locks on, it can pull part or all of the virus inside and present coronavirus fragments on its surface.\n\nA helper T cell activated against the coronavirus can latch onto the same fragment. When that happens, the B cell gets activated, too. It proliferates and pours out antibodies that have the same shape as their surface proteins.\n\n![](https:\/\/static01.nyt.com\/newsgraphics\/2020\/12\/05\/how-coronavirus-vaccines-work\/223b8183b7e9cde2b16745b6f17504082c328540\/6-bcell-sinovac-900.png)\n\nACTIVATED\n\nHELPER\n\nT CELL\n\nINACTIVATED\n\nCORONAVIRUS\n\nActivating\n\nthe B cell\n\nMatching\n\nsurface proteins\n\nB CELL\n\nSECRETED\n\nANTIBODIES\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nACTIVATED\n\nHELPER\n\nT CELL\n\nINACTIVATED\n\nCORONAVIRUS\n\nActivating\n\nthe B cell\n\nMatching\n\nsurface proteins\n\nB CELL\n\nSECRETED\n\nANTIBODIES\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nACTIVATED\n\nHELPER\n\nT CELL\n\nINACTIVATED\n\nCORONAVIRUS\n\nActivating\n\nthe B cell\n\nMatching\n\nsurface proteins\n\nB CELL\n\nSECRETED\n\nANTIBODIES\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nACTIVATED\n\nHELPER\n\nT CELL\n\nINACTIVATED\n\nCORONAVIRUS\n\nActivating\n\nthe B cell\n\nMatching\n\nsurface proteins\n\nB CELL\n\nSECRETED\n\nANTIBODIES\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nACTIVATED\n\nHELPER\n\nT CELL\n\nINACTIVATED\n\nCORONAVIRUS\n\nActivating\n\nthe B cell\n\nMatching\n\nsurface proteins\n\nB CELL\n\nSECRETED\n\nANTIBODIES\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nACTIVATED\n\nHELPER\n\nT CELL\n\nINACTIVATED\n\nCORONAVIRUS\n\nActivating\n\nthe B cell\n\nMatching\n\nsurface proteins\n\nB CELL\n\nSECRETED\n\nANTIBODIES\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nACTIVATED\n\nHELPER\n\nT CELL\n\nActivating\n\nthe B cell\n\nB CELL\n\nMatching\n\nsurface\n\nproteins\n\nINACTIVATED\n\nCORONAVIRUS\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nACTIVATED\n\nHELPER\n\nT CELL\n\nActivating\n\nthe B cell\n\nB CELL\n\nMatching\n\nsurface\n\nproteins\n\nINACTIVATED\n\nCORONAVIRUS\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nACTIVATED\n\nHELPER\n\nT CELL\n\nActivating\n\nthe B cell\n\nB CELL\n\nMatching\n\nsurface\n\nproteins\n\nINACTIVATED\n\nCORONAVIRUS\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nACTIVATED\n\nHELPER\n\nT CELL\n\nActivating\n\nthe B cell\n\nB CELL\n\nMatching\n\nsurface proteins\n\nINACTIVATED\n\nCORONAVIRUS\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nACTIVATED\n\nHELPER\n\nT CELL\n\nActivating\n\nthe B cell\n\nB CELL\n\nMatching\n\nsurface proteins\n\nINACTIVATED\n\nCORONAVIRUS\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nACTIVATED\n\nHELPER\n\nT CELL\n\nActivating\n\nthe B cell\n\nB CELL\n\nMatching\n\nsurface proteins\n\nINACTIVATED\n\nCORONAVIRUS\n## Stopping the Virus\nOnce vaccinated with CoronaVac, the immune system can respond to an infection of live coronaviruses. B cells produce antibodies that stick to the invaders. Antibodies that target the spike protein can prevent the virus from entering cells. Other kinds of antibodies may block the virus by other means.\n\n![](https:\/\/static01.nyt.com\/newsgraphics\/2020\/12\/05\/how-coronavirus-vaccines-work\/223b8183b7e9cde2b16745b6f17504082c328540\/7-antibodies-sinovac-600.png)\n\nANTIBODIES\n\nLIVE\n\nVIRUS\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nANTIBODIES\n\nLIVE\n\nVIRUS\n\n![](data:image\/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==)\n\nANTIBODIES\n\nLIVE\n\nVIRUS\n## Remembering the Virus\nWhile CoronaVac can offer some protection against Covid-19, no one can yet say how long that protection lasts. It’s possible that the level of antibodies drops over the course of months. But the immune system also contains special cells called memory B cells that might retain information about the coronavirus for years or even decades.\n\n## Vaccine Timeline\n**January, 2020** Sinovac begins developing an inactivated vaccine against the coronavirus.\n\n![](https:\/\/static01.nyt.com\/newsgraphics\/2020\/12\/05\/how-coronavirus-vaccines-work\/assets\/images\/sinovac-cells-600.jpg)\n\n![](https:\/\/static01.nyt.com\/newsgraphics\/2020\/12\/05\/how-coronavirus-vaccines-work\/assets\/images\/sinovac-cells-1050.jpg)\n\nSinovac engineers working with monkey kidney cells.Nicolas Asfouri\/Agence France-Presse\n\n**June** Phase 1\/2 trials on 743 volunteers find [no severe adverse effects](https:\/\/www.medrxiv.org\/content\/10.1101\/2020.07.31.20161216v1).\n\n**July** Sinovac launches a Phase 3 trial in Brazil, followed by others in [Indonesia](https:\/\/www.reuters.com\/article\/us-health-coronavirus-indonesia-vaccine\/sinovac-launches-phase-3-trial-for-covid-19-vaccine-in-indonesia-reports-phase-2-details-idUSKCN2570E9) and [Turkey](http:\/\/www.sinovac.com\/?optionid=754&auto_id=911). Reuters [reports](https:\/\/www.nytimes.com\/reuters\/2020\/08\/28\/world\/asia\/28reuters-health-coronavirus-china-vaccines.html) that the Chinese government gave the Sinovac vaccine emergency approval for limited use.\n\n![](https:\/\/static01.nyt.com\/newsgraphics\/2020\/12\/05\/how-coronavirus-vaccines-work\/assets\/images\/sinovac-syringe-600.jpg)\n\n![](https:\/\/static01.nyt.com\/newsgraphics\/2020\/12\/05\/how-coronavirus-vaccines-work\/assets\/images\/sinovac-syringe-1050.jpg)\n\nA dose of CoronaVac in Turkey.Emrah Gurel\/Associated Press\n\n**October** Authorities in the eastern Chinese city of Jiaxing announce they are [giving CoronaVac](https:\/\/www.nytimes.com\/live\/2020\/10\/16\/world\/covid-coronavirus\/a-chinese-city-says-it-has-given-some-residents-a-vaccine-and-other-news-from-around-the-world) to people in relatively high-risk jobs, including medical workers, port inspectors and public service personnel.\n\n**Oct. 19** Officials in Brazil [say](https:\/\/fortune.com\/2020\/10\/20\/covid-vaccine-china-brazil-testing-ground-safest-most-promising-sinovac\/) that Sinovac is the safest of five vaccines they are testing in Phase 3 trials.\n\n**November** Sinovac [publishes](https:\/\/www.thelancet.com\/journals\/laninf\/article\/PIIS1473-3099\$20\$30843-4\/fulltext) the details of its Phase 1\/2 trial in a medical journal, showing a comparatively modest production of antibodies. Only a Phase 3 trial will demonstrate if that is enough to protect people from Covid-19.\n\n**Nov. 19** The Brazilian government [announces](https:\/\/www.nytimes.com\/2020\/11\/10\/world\/asia\/brazil-china-vaccine-covid19.html) that they paused the country’s Sinovac trial the previous month because of an adverse event. The details of the pause were murky, raising suspicions that politics were involved. Two days after the announcement, the trial was [allowed to resume](https:\/\/www.nytimes.com\/2020\/11\/11\/world\/brazil-resumes-chinese-vaccine-trial-after-a-brief-suspension-following-the-death-of-a-volunteer.html). The Brazilian trial has recorded enough cases of Covid-19 to let researchers determine Sinovac’s efficacy. They expect to release their results by Dec. 23.\n\n![](https:\/\/static01.nyt.com\/newsgraphics\/2020\/12\/05\/how-coronavirus-vaccines-work\/assets\/images\/sinovac-brazil-600.jpg)\n\n![](https:\/\/static01.nyt.com\/newsgraphics\/2020\/12\/05\/how-coronavirus-vaccines-work\/assets\/images\/sinovac-brazil-1050.jpg)\n\nOfficials in Brazil hold boxes from a shipment of the vaccine.Alexandre Schneider\/Getty Images\n\n**December** Sinovac [says](https:\/\/www.businesswire.com\/news\/home\/20201206005056\/en\/Sinovac-Secures-Approximately-500-Million-in-Funding-for-COVID-19-Vaccine-Development) it expects to manufacture 300 million doses in 2020 and increase capacity to an annual production of 600 million doses.\n\n**Dec. 23** Brazilian researchers announce that CoronaVac has an efficacy of [over 50 percent](https:\/\/www.reuters.com\/article\/us-health-coronavirus-sinovac-brazil\/brazil-institute-says-coronavac-efficacy-above-50-but-delays-full-results-idUSKBN28X2CR).\n\n**Dec. 24** Turkish officials announce that the vaccine has an efficacy rate of [91\\.25 percent](https:\/\/www.nytimes.com\/2020\/12\/25\/health\/turkey-brazil-sinovac-coronavirus-vaccine.html).\n\n**Jan. 7, 2021** Researchers in Brazil [announce](https:\/\/www.nytimes.com\/2021\/01\/07\/business\/china-coronavirus-vaccine-sinovac.html) that CoronaVac has an efficacy of 78 percent. None of the vaccinated volunteers in their Phase 3 trial developed severe or moderate cases of Covid-19. But the efficacy estimate was based on the vaccine’s performance in a subgroup of volunteers. The overall efficacy is not formally released.\n\n**Jan. 11** [Indonesia](https:\/\/www.reuters.com\/article\/us-health-coronavirus-indonesia\/indonesia-approves-chinas-sinovac-vaccine-as-infections-surge-idUSKBN29G0RP) authorizes the vaccine for emergency use.\n\n**Jan. 13** Researchers in Brazil [announce](https:\/\/www.nytimes.com\/2021\/01\/13\/business\/chinese-vaccine-brazil-sinovac.html) that CoronaVac has an overall efficacy of just over 50 percent. Turkey authorizes the vaccine for emergency use.\n\n**Feb. 6** Sinovac announces that China has given CoronaVac [conditional approval](https:\/\/www.nytimes.com\/live\/2021\/02\/06\/world\/covid-19-coronavirus#china-approves-a-second-covid-19-vaccine-and-other-news-from-around-the-world).\n\n**March 13** China asks visa applicants to get [inoculated with Chinese-made coronavirus vaccines](https:\/\/www.nytimes.com\/2021\/03\/12\/world\/china-vaccines-hong-kong.html).\n\n**April 1** Sinovac [announces](https:\/\/www.businesswire.com\/news\/home\/20210401005993\/en\/Sinovac%C2%A0Announced-Buildup-of-Two-Billion-Annual-Capacity-of-Its-COVID-19-Vaccine) that its capacity has increased to 2 billion doses after completing a third production line.\n\nSources: National Center for Biotechnology Information; Science; The Lancet; Lynda Coughlan, University of Maryland School of Medicine; Jenna Guthmiller, University of Chicago.\n\n## Tracking the Coronavirus\n### United States\n- [Latest Maps and Data Cases and deaths for every county](https:\/\/www.nytimes.com\/interactive\/2021\/us\/covid-cases.html)\n- [Vaccinations How many have been vaccinated, and who’s eligible](https:\/\/www.nytimes.com\/interactive\/2020\/us\/covid-19-vaccine-doses.html)\n- [Your Places Build your own dashboard to track cases](https:\/\/www.nytimes.com\/interactive\/2021\/us\/covid-cases-deaths-tracker.html)\n- [Hospitals Near You How many I.C.U. beds are occupied](https:\/\/www.nytimes.com\/interactive\/2020\/us\/covid-hospitals-near-you.html)\n### World\n- [Latest Maps and Data Cases and deaths for every country](https:\/\/www.nytimes.com\/interactive\/2021\/world\/covid-cases.html)\n- [Global Vaccinations How many have been vaccinated, by country](https:\/\/www.nytimes.com\/interactive\/2021\/world\/covid-vaccinations-tracker.html)\n### Health\n- [Vaccines Track their development](https:\/\/www.nytimes.com\/interactive\/2020\/science\/coronavirus-vaccine-tracker.html)\n- [Treatments Rated by effectiveness and safety](https:\/\/www.nytimes.com\/interactive\/2020\/science\/coronavirus-drugs-treatments.html)\n### Previous Projects\n- [Mask Mandates See state mask guidance for schools and indoors](https:\/\/www.nytimes.com\/interactive\/2021\/us\/cdc-mask-guidance-states.html)\n- [Your County’s Risk See guidance for your local area](https:\/\/www.nytimes.com\/interactive\/2021\/us\/covid-risk-map.html)\n- [Nursing Homes The hardest-hit states and facilities](https:\/\/www.nytimes.com\/interactive\/2020\/us\/coronavirus-nursing-homes.html)\n- [Colleges and Universities Cases at more than 1,800 schools](https:\/\/www.nytimes.com\/interactive\/2021\/us\/college-covid-tracker.html)\n- [Deaths Above Normal The true toll of the pandemic in the U.S.](https:\/\/www.nytimes.com\/interactive\/2021\/01\/14\/us\/covid-19-death-toll.html)\n- [Deaths Above Normal The true toll of coronavirus around the world](https:\/\/www.nytimes.com\/interactive\/2020\/04\/21\/world\/coronavirus-missing-deaths.html)\n- [Early Coronavirus Outbreaks Cases in nursing homes, prisons and other places](https:\/\/www.nytimes.com\/interactive\/2021\/us\/covid-case-outbreaks.html)\n### Countries\n- [Australia](https:\/\/www.nytimes.com\/interactive\/2021\/world\/australia-covid-cases.html)\n- [Brazil](https:\/\/www.nytimes.com\/interactive\/2021\/world\/brazil-covid-cases.html)\n- [Canada](https:\/\/www.nytimes.com\/interactive\/2021\/world\/canada-covid-cases.html)\n- [China](https:\/\/www.nytimes.com\/interactive\/2021\/world\/china-covid-cases.html)\n- [France](https:\/\/www.nytimes.com\/interactive\/2021\/world\/france-covid-cases.html)\n- [Germany](https:\/\/www.nytimes.com\/interactive\/2021\/world\/germany-covid-cases.html)\n- [India](https:\/\/www.nytimes.com\/interactive\/2021\/world\/india-covid-cases.html)\n- [Italy](https:\/\/www.nytimes.com\/interactive\/2021\/world\/italy-covid-cases.html)\n- [Japan](https:\/\/www.nytimes.com\/interactive\/2021\/world\/japan-covid-cases.html)\n- [Mexico](https:\/\/www.nytimes.com\/interactive\/2021\/world\/mexico-covid-cases.html)\n- [South Africa](https:\/\/www.nytimes.com\/interactive\/2021\/world\/south-africa-covid-cases.html)\n- [Spain](https:\/\/www.nytimes.com\/interactive\/2021\/world\/spain-covid-cases.html)\n- [United Kingdom](https:\/\/www.nytimes.com\/interactive\/2021\/world\/united-kingdom-covid-cases.html)\n- [United States](https:\/\/www.nytimes.com\/interactive\/2021\/us\/covid-cases.html)\n### States, Territories and Cities\n- [Alabama](https:\/\/www.nytimes.com\/interactive\/2021\/us\/alabama-covid-cases.html)\n- [Alaska](https:\/\/www.nytimes.com\/interactive\/2021\/us\/alaska-covid-cases.html)\n- [Arizona](https:\/\/www.nytimes.com\/interactive\/2021\/us\/arizona-covid-cases.html)\n- [Arkansas](https:\/\/www.nytimes.com\/interactive\/2021\/us\/arkansas-covid-cases.html)\n- [California](https:\/\/www.nytimes.com\/interactive\/2021\/us\/california-covid-cases.html)\n- [Colorado](https:\/\/www.nytimes.com\/interactive\/2021\/us\/colorado-covid-cases.html)\n- [Connecticut](https:\/\/www.nytimes.com\/interactive\/2021\/us\/connecticut-covid-cases.html)\n- [Delaware](https:\/\/www.nytimes.com\/interactive\/2021\/us\/delaware-covid-cases.html)\n- [Florida](https:\/\/www.nytimes.com\/interactive\/2021\/us\/florida-covid-cases.html)\n- [Georgia](https:\/\/www.nytimes.com\/interactive\/2021\/us\/georgia-covid-cases.html)\n- [Guam](https:\/\/www.nytimes.com\/interactive\/2021\/us\/guam-covid-cases.html)\n- [Hawaii](https:\/\/www.nytimes.com\/interactive\/2021\/us\/hawaii-covid-cases.html)\n- [Idaho](https:\/\/www.nytimes.com\/interactive\/2021\/us\/idaho-covid-cases.html)\n- [Illinois](https:\/\/www.nytimes.com\/interactive\/2021\/us\/illinois-covid-cases.html)\n- [Indiana](https:\/\/www.nytimes.com\/interactive\/2021\/us\/indiana-covid-cases.html)\n- [Iowa](https:\/\/www.nytimes.com\/interactive\/2021\/us\/iowa-covid-cases.html)\n- [Kansas](https:\/\/www.nytimes.com\/interactive\/2021\/us\/kansas-covid-cases.html)\n- [Kentucky](https:\/\/www.nytimes.com\/interactive\/2021\/us\/kentucky-covid-cases.html)\n- [Louisiana](https:\/\/www.nytimes.com\/interactive\/2021\/us\/louisiana-covid-cases.html)\n- [Maine](https:\/\/www.nytimes.com\/interactive\/2021\/us\/maine-covid-cases.html)\n- [Maryland](https:\/\/www.nytimes.com\/interactive\/2021\/us\/maryland-covid-cases.html)\n- [Massachusetts](https:\/\/www.nytimes.com\/interactive\/2021\/us\/massachusetts-covid-cases.html)\n- [Michigan](https:\/\/www.nytimes.com\/interactive\/2021\/us\/michigan-covid-cases.html)\n- [Minnesota](https:\/\/www.nytimes.com\/interactive\/2021\/us\/minnesota-covid-cases.html)\n- [Mississippi](https:\/\/www.nytimes.com\/interactive\/2021\/us\/mississippi-covid-cases.html)\n- [Missouri](https:\/\/www.nytimes.com\/interactive\/2021\/us\/missouri-covid-cases.html)\n- [Montana](https:\/\/www.nytimes.com\/interactive\/2021\/us\/montana-covid-cases.html)\n- [Nebraska](https:\/\/www.nytimes.com\/interactive\/2021\/us\/nebraska-covid-cases.html)\n- [Nevada](https:\/\/www.nytimes.com\/interactive\/2021\/us\/nevada-covid-cases.html)\n- [New Hampshire](https:\/\/www.nytimes.com\/interactive\/2021\/us\/new-hampshire-covid-cases.html)\n- [New Jersey](https:\/\/www.nytimes.com\/interactive\/2021\/us\/new-jersey-covid-cases.html)\n- [New Mexico](https:\/\/www.nytimes.com\/interactive\/2021\/us\/new-mexico-covid-cases.html)\n- [New York](https:\/\/www.nytimes.com\/interactive\/2021\/us\/new-york-covid-cases.html)\n- [North Carolina](https:\/\/www.nytimes.com\/interactive\/2021\/us\/north-carolina-covid-cases.html)\n- [North Dakota](https:\/\/www.nytimes.com\/interactive\/2021\/us\/north-dakota-covid-cases.html)\n- [Northern Mariana Islands](https:\/\/www.nytimes.com\/interactive\/2021\/us\/northern-mariana-islands-covid-cases.html)\n- [Ohio](https:\/\/www.nytimes.com\/interactive\/2021\/us\/ohio-covid-cases.html)\n- [Oklahoma](https:\/\/www.nytimes.com\/interactive\/2021\/us\/oklahoma-covid-cases.html)\n- [Oregon](https:\/\/www.nytimes.com\/interactive\/2021\/us\/oregon-covid-cases.html)\n- [Pennsylvania](https:\/\/www.nytimes.com\/interactive\/2021\/us\/pennsylvania-covid-cases.html)\n- [Puerto Rico](https:\/\/www.nytimes.com\/interactive\/2021\/us\/puerto-rico-covid-cases.html)\n- [Rhode Island](https:\/\/www.nytimes.com\/interactive\/2021\/us\/rhode-island-covid-cases.html)\n- [South Carolina](https:\/\/www.nytimes.com\/interactive\/2021\/us\/south-carolina-covid-cases.html)\n- [South Dakota](https:\/\/www.nytimes.com\/interactive\/2021\/us\/south-dakota-covid-cases.html)\n- [Tennessee](https:\/\/www.nytimes.com\/interactive\/2021\/us\/tennessee-covid-cases.html)\n- [Texas](https:\/\/www.nytimes.com\/interactive\/2021\/us\/texas-covid-cases.html)\n- [U.S. Virgin Islands](https:\/\/www.nytimes.com\/interactive\/2021\/us\/virgin-islands-covid-cases.html)\n- [Utah](https:\/\/www.nytimes.com\/interactive\/2021\/us\/utah-covid-cases.html)\n- [Vermont](https:\/\/www.nytimes.com\/interactive\/2021\/us\/vermont-covid-cases.html)\n- [Virginia](https:\/\/www.nytimes.com\/interactive\/2021\/us\/virginia-covid-cases.html)\n- [Washington](https:\/\/www.nytimes.com\/interactive\/2021\/us\/washington-covid-cases.html)\n- [Washington, D.C.](https:\/\/www.nytimes.com\/interactive\/2021\/us\/washington-district-of-columbia-covid-cases.html)\n- [West Virginia](https:\/\/www.nytimes.com\/interactive\/2021\/us\/west-virginia-covid-cases.html)\n- [Wisconsin](https:\/\/www.nytimes.com\/interactive\/2021\/us\/wisconsin-covid-cases.html)\n- [Wyoming](https:\/\/www.nytimes.com\/interactive\/2021\/us\/wyoming-covid-cases.html)\n### Data\n- [Frequently Asked Questions About the Covid Data](https:\/\/www.nytimes.com\/interactive\/2020\/us\/about-coronavirus-data-maps.html)\n- [Access the Open Source Covid Data](https:\/\/github.com\/nytimes\/covid-19-data)\n\nAdd a comment\n\n- Share full article\n- 0\n\n## Related Content\n### [More in Health](https:\/\/www.nytimes.com\/section\/health)\n- [Cancer Haunts Neighbors of Canada’s Oil Sands Wastelands](https:\/\/www.nytimes.com\/2026\/03\/10\/health\/canada-oil-sands-fort-chipewyan-alberta.html)\n  \n  ![A Syncrude facility near Fort McMurray, Alberta.](https:\/\/static01.nyt.com\/images\/2026\/03\/10\/multimedia\/00hs-oil-sands-health-03-qhmk\/00hs-oil-sands-health-03-qhmk-square640.jpg?quality=75&auto=webp&disable=upscale)\n  \n  Pat Kane for The New York Times\n- [From 2001: Beate Uhse, 81, Entrepreneur in the Business of Erotic Goods](https:\/\/www.nytimes.com\/2026\/03\/06\/world\/europe\/beate-uhse-dead.html)\n  \n  ![Beate Uhse in 1971, in front of her mail-order company headquarters in Flensburg, Germany.](https:\/\/static01.nyt.com\/images\/2026\/03\/06\/obituaries\/06whm-uhse-obit\/06whm-uhse-obit-square640.jpg?quality=75&auto=webp&disable=upscale)\n  \n  Hesslefors\/ullstein bild, via Getty Images\n- [Most Patients Keep Weight Off With Fewer GLP-1 Shots, Study Finds](https:\/\/www.nytimes.com\/2026\/03\/04\/health\/glp1-weight-loss-dosing.html)\n  \n  ![](https:\/\/static01.nyt.com\/images\/2026\/03\/04\/multimedia\/04HS-weight-loss-zgtw\/04HS-weight-loss-zgtw-square640.jpg?quality=75&auto=webp&disable=upscale)\n  \n  Kristian Thacker for The New York Times\n- [Banks Are Becoming Bulwarks for Vulnerable Seniors](https:\/\/www.nytimes.com\/2026\/02\/28\/health\/scams-elderly-banks.html)\n  \n  ![](https:\/\/static01.nyt.com\/images\/2026\/03\/03\/science\/03sci-SPAN-financial-predators\/03sci-SPAN-financial-predators-square640.jpg?quality=75&auto=webp&disable=upscale)\n  \n  Federica Bordoni\n\n### Editors’ Picks\n- [He Grew Up Watching Her on TV. Years Later, She Joined His World.](https:\/\/www.nytimes.com\/2026\/03\/06\/style\/brooke-hyland-brian-thalman-wedding.html)\n  \n  ![](https:\/\/static01.nyt.com\/images\/2026\/03\/08\/style\/00MINI-HYLAND-THALMAN\/00MINI-HYLAND-THALMAN-square640.jpg?quality=75&auto=webp&disable=upscale)\n  \n  Aislinn Rose Photography\n- [My Sister’s Crime Shattered Our Family. Do I Have to Help Her?](https:\/\/www.nytimes.com\/2026\/03\/07\/magazine\/sisters-crime-family-ethics.html)\n  \n  ![](https:\/\/static01.nyt.com\/images\/2026\/03\/14\/magazine\/14mag-ethicist\/14mag-ethicist-square640.jpg?quality=75&auto=webp&disable=upscale)\n  \n  Illustration by Tomi Um\n\n### Trending in The Times\n- [Alabama Governor Spares Death Row Inmate Who Didn’t Pull the Trigger](https:\/\/www.nytimes.com\/2026\/03\/10\/us\/alabama-ivey-charles-burton.html)\n  \n  ![Death penalty opponents had flooded the governor’s office in recent days with pleas to spare Charles Burton.](https:\/\/static01.nyt.com\/images\/2026\/03\/05\/multimedia\/10nat-alabama-execution1\/05Vartkessian-jwkv-square640.jpg?quality=75&auto=webp&disable=upscale&width=350)\n  \n  Matt Schulz, via Associated Press\n- [First, They Were Just Fishing. Then the Ice Started Moving.](https:\/\/www.nytimes.com\/2026\/03\/09\/world\/canada\/fishermen-ice-shelf-rescue-canada.html)\n  \n  ![Nearly two dozen people were rescued after they were stranded on breakaway ice by Georgian Bay, north of Toronto, on Sunday.](https:\/\/static01.nyt.com\/images\/2026\/03\/09\/multimedia\/09xp-fishing1\/09xp-fishing-square640.jpg?quality=75&auto=webp&disable=upscale&width=350)\n  \n  Ontario Provincial Police\n- [After a Stroke, Working a Runway Without Walking](https:\/\/www.nytimes.com\/2026\/03\/08\/style\/miss-j-americas-next-top-model.html)\n  \n  ![J. Alexander at Netflix’s office in Manhattan. 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Here’s What to Know.](https:\/\/www.nytimes.com\/2026\/03\/10\/travel\/airline-prices-mideast-war.html)\n  \n  ![How much the cost of an airline ticket may rise is unclear. The last time oil rose more than 40 percent — in 2022, on the heels of Russia’s invasion of Ukraine — airfares jumped 28 percent.](https:\/\/static01.nyt.com\/images\/2026\/03\/09\/multimedia\/00Trav-Airline-Prices-Gulf-Conflict-cmbz\/00Trav-Airline-Prices-Gulf-Conflict-cmbz-square640-v2.jpg?quality=75&auto=webp&disable=upscale&width=350)\n  \n  Raghed Waked\/Reuters\n- [Opinion: Trump Has No Idea How to End the War With Iran](https:\/\/www.nytimes.com\/2026\/03\/09\/opinion\/iran-israel-united-states-bombing.html)\n  \n  ![](https:\/\/static01.nyt.com\/images\/2026\/03\/10\/multimedia\/09friedman-jkbc\/09friedman-jkbc-square640.jpg?quality=75&auto=webp&disable=upscale&width=350)\n  \n  Nanna Heitmann for The New York Times\n- [Forget Florida. They Got Older and Moved to New York.](https:\/\/www.nytimes.com\/2026\/03\/07\/nyregion\/older-adults-nyc-move.html)\n  \n  ![Bob Krinsky, 65, moved to a two-bedroom apartment with sweeping, 47th-floor views of the Manhattan skyline to be closer to his two grown sons after his 30-year marriage ended. ](https:\/\/static01.nyt.com\/images\/2026\/03\/07\/multimedia\/07met-older-new-yorkers-vhqw\/07met-older-new-yorkers-vhqw-square640.jpg?quality=75&auto=webp&disable=upscale&width=350)\n- [U.S. Authorities Are Investigating Device Thrown Near Gracie Mansion](https:\/\/www.nytimes.com\/2026\/03\/08\/nyregion\/gracie-mansion-bomb-investigation.html)\n  \n  ![Emir Balat runs as police officers approach and a homemade bomb starts to emit smoke outside Gracie Mansion on Saturday.](https:\/\/static01.nyt.com\/images\/2026\/03\/08\/multimedia\/08METGracie-bfvj\/08METGracie-bfvj-square640.jpg?quality=75&auto=webp&disable=upscale&width=350)\n  \n  Vincent Alban\/The New York Times\n- [Map: 2.3-Magnitude Earthquake Reported North of New York City](https:\/\/www.nytimes.com\/interactive\/2026\/03\/10\/us\/quake-tracker-new-york.html)\n  \n  ![](https:\/\/static01.nyt.com\/images\/2026\/03\/10\/world\/10wea-quake-tracker-new-york-nyt9fmg5-index\/10wea-quake-tracker-new-york-nyt9fmg5-index-square640-v44.jpg?quality=75&auto=webp&disable=upscale&width=350)\n  \n  The New York Times\n\nAdvertisement\n\n[SKIP ADVERTISEMENT](https:\/\/www.nytimes.com\/interactive\/2020\/health\/sinovac-covid-19-vaccine.html#after-bottom)\n\n## Site Index\n[Go to Home Page »](https:\/\/www.nytimes.com\/)\n\nNews\n\n- [Home Page](https:\/\/www.nytimes.com\/)\n- [U.S.](https:\/\/www.nytimes.com\/section\/us)\n- [World](https:\/\/www.nytimes.com\/section\/world)\n- [Politics](https:\/\/www.nytimes.com\/section\/politics)\n- [New York](https:\/\/www.nytimes.com\/section\/nyregion)\n- [Education](https:\/\/www.nytimes.com\/section\/education)\n- [Sports](https:\/\/www.nytimes.com\/section\/sports)\n- 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Close nav\n\nWorld Close nav\n\nHealth Close nav\n\nThe private Chinese company Sinovac developed a [coronavirus vaccine](https:\/\/www.nytimes.com\/interactive\/2020\/science\/coronavirus-vaccine-tracker.html#sinovac) called **CoronaVac**. The vaccine is approved for use in China and authorized for emergency use in more than a dozen other countries. In a trial in Brazil, researchers found it had an efficacy against infections with or without symptoms of [50\\.65 percent](https:\/\/www.nytimes.com\/2021\/01\/13\/business\/chinese-vaccine-brazil-sinovac.html). In a trial in Turkey, researchers found it had an efficacy of 91.25 percent against Covid-19 infections with symptoms.\n\n## A Vaccine Made From Coronaviruses\nCoronaVac works by teaching the immune system to make antibodies against the SARS-CoV-2 coronavirus. The antibodies attach to viral proteins, such as the so-called spike proteins that [stud its surface](https:\/\/www.nytimes.com\/interactive\/2020\/health\/coronavirus-unveiled.html).\n\nTo create CoronaVac, the Sinovac researchers started by obtaining samples of the coronavirus from patients in China, Britain, Italy, Spain and Switzerland. One sample from China eventually served as the basis for the vaccine.\n\n## Killing the Virus\nThe researchers grew large stocks of the coronavirus in monkey kidney cells. Then they doused the viruses with a chemical called beta-propiolactone. The compound disabled the coronaviruses by bonding to their genes. The inactivated coronaviruses could no longer replicate. But their proteins, including spike, remained intact.\n\nThe researchers then drew off the inactivated viruses and mixed them with a tiny amount of an aluminum-based compound called an adjuvant. Adjuvants stimulate the immune system to boost its response to a vaccine.\n\nInactivated viruses have been used for over a century. Jonas Salk used them to create his [polio vaccine](https:\/\/www.nytimes.com\/1955\/04\/13\/archives\/salk-polio-vaccine-proves-success-millions-will-be-immunized-soon.html) in the 1950s, and they’re the bases for vaccines against other diseases including [rabies](https:\/\/www.nytimes.com\/1973\/08\/21\/archives\/vaccine-for-rabies-developed-cutting-shots-from-14-to-1-vaccine.html) and [hepatitis A](https:\/\/www.nytimes.com\/1992\/08\/13\/us\/test-indicates-new-vaccine-works-against-hepatitis-a.html).\n\n## Prompting an Immune Response\nBecause the coronaviruses in CoronaVac are dead, they can be injected into the arm without causing Covid-19. Once inside the body, some of the inactivated viruses are swallowed up by a type of immune cell called an antigen-presenting cell.\n\nThe antigen-presenting cell tears the coronavirus apart and displays some of its fragments on its surface. A so-called helper T cell may detect the fragment. If the fragment fits into one of its surface proteins, the T cell becomes activated and can help recruit other immune cells to respond to the vaccine.\n\n## Making Antibodies\nAnother type of immune cell, called a B cell, may also encounter the inactivated coronavirus. B cells have surface proteins in a huge variety of shapes, and a few might have the right shape to latch onto the coronavirus. When a B cell locks on, it can pull part or all of the virus inside and present coronavirus fragments on its surface.\n\nA helper T cell activated against the coronavirus can latch onto the same fragment. When that happens, the B cell gets activated, too. It proliferates and pours out antibodies that have the same shape as their surface proteins.\n\n## Stopping the Virus\nOnce vaccinated with CoronaVac, the immune system can respond to an infection of live coronaviruses. B cells produce antibodies that stick to the invaders. Antibodies that target the spike protein can prevent the virus from entering cells. Other kinds of antibodies may block the virus by other means.\n\n## Remembering the Virus\nWhile CoronaVac can offer some protection against Covid-19, no one can yet say how long that protection lasts. It’s possible that the level of antibodies drops over the course of months. But the immune system also contains special cells called memory B cells that might retain information about the coronavirus for years or even decades.\n\n## Vaccine Timeline\n**January, 2020** Sinovac begins developing an inactivated vaccine against the coronavirus.\n\n![](https:\/\/static01.nyt.com\/newsgraphics\/2020\/12\/05\/how-coronavirus-vaccines-work\/assets\/images\/sinovac-cells-1050.jpg)\n\nSinovac engineers working with monkey kidney cells.Nicolas Asfouri\/Agence France-Presse\n\n**June** Phase 1\/2 trials on 743 volunteers find [no severe adverse effects](https:\/\/www.medrxiv.org\/content\/10.1101\/2020.07.31.20161216v1).\n\n**July** Sinovac launches a Phase 3 trial in Brazil, followed by others in [Indonesia](https:\/\/www.reuters.com\/article\/us-health-coronavirus-indonesia-vaccine\/sinovac-launches-phase-3-trial-for-covid-19-vaccine-in-indonesia-reports-phase-2-details-idUSKCN2570E9) and [Turkey](http:\/\/www.sinovac.com\/?optionid=754&auto_id=911). Reuters [reports](https:\/\/www.nytimes.com\/reuters\/2020\/08\/28\/world\/asia\/28reuters-health-coronavirus-china-vaccines.html) that the Chinese government gave the Sinovac vaccine emergency approval for limited use.\n\n![](https:\/\/static01.nyt.com\/newsgraphics\/2020\/12\/05\/how-coronavirus-vaccines-work\/assets\/images\/sinovac-syringe-1050.jpg)\n\nA dose of CoronaVac in Turkey.Emrah Gurel\/Associated Press\n\n**October** Authorities in the eastern Chinese city of Jiaxing announce they are [giving CoronaVac](https:\/\/www.nytimes.com\/live\/2020\/10\/16\/world\/covid-coronavirus\/a-chinese-city-says-it-has-given-some-residents-a-vaccine-and-other-news-from-around-the-world) to people in relatively high-risk jobs, including medical workers, port inspectors and public service personnel.\n\n**Oct. 19** Officials in Brazil [say](https:\/\/fortune.com\/2020\/10\/20\/covid-vaccine-china-brazil-testing-ground-safest-most-promising-sinovac\/) that Sinovac is the safest of five vaccines they are testing in Phase 3 trials.\n\n**November** Sinovac [publishes](https:\/\/www.thelancet.com\/journals\/laninf\/article\/PIIS1473-3099\$20\$30843-4\/fulltext) the details of its Phase 1\/2 trial in a medical journal, showing a comparatively modest production of antibodies. Only a Phase 3 trial will demonstrate if that is enough to protect people from Covid-19.\n\n**Nov. 19** The Brazilian government [announces](https:\/\/www.nytimes.com\/2020\/11\/10\/world\/asia\/brazil-china-vaccine-covid19.html) that they paused the country’s Sinovac trial the previous month because of an adverse event. The details of the pause were murky, raising suspicions that politics were involved. Two days after the announcement, the trial was [allowed to resume](https:\/\/www.nytimes.com\/2020\/11\/11\/world\/brazil-resumes-chinese-vaccine-trial-after-a-brief-suspension-following-the-death-of-a-volunteer.html). The Brazilian trial has recorded enough cases of Covid-19 to let researchers determine Sinovac’s efficacy. They expect to release their results by Dec. 23.\n\n![](https:\/\/static01.nyt.com\/newsgraphics\/2020\/12\/05\/how-coronavirus-vaccines-work\/assets\/images\/sinovac-brazil-1050.jpg)\n\nOfficials in Brazil hold boxes from a shipment of the vaccine.Alexandre Schneider\/Getty Images\n\n**December** Sinovac [says](https:\/\/www.businesswire.com\/news\/home\/20201206005056\/en\/Sinovac-Secures-Approximately-500-Million-in-Funding-for-COVID-19-Vaccine-Development) it expects to manufacture 300 million doses in 2020 and increase capacity to an annual production of 600 million doses.\n\n**Dec. 23** Brazilian researchers announce that CoronaVac has an efficacy of [over 50 percent](https:\/\/www.reuters.com\/article\/us-health-coronavirus-sinovac-brazil\/brazil-institute-says-coronavac-efficacy-above-50-but-delays-full-results-idUSKBN28X2CR).\n\n**Dec. 24** Turkish officials announce that the vaccine has an efficacy rate of [91\\.25 percent](https:\/\/www.nytimes.com\/2020\/12\/25\/health\/turkey-brazil-sinovac-coronavirus-vaccine.html).\n\n**Jan. 7, 2021** Researchers in Brazil [announce](https:\/\/www.nytimes.com\/2021\/01\/07\/business\/china-coronavirus-vaccine-sinovac.html) that CoronaVac has an efficacy of 78 percent. None of the vaccinated volunteers in their Phase 3 trial developed severe or moderate cases of Covid-19. But the efficacy estimate was based on the vaccine’s performance in a subgroup of volunteers. The overall efficacy is not formally released.\n\n**Jan. 11** [Indonesia](https:\/\/www.reuters.com\/article\/us-health-coronavirus-indonesia\/indonesia-approves-chinas-sinovac-vaccine-as-infections-surge-idUSKBN29G0RP) authorizes the vaccine for emergency use.\n\n**Jan. 13** Researchers in Brazil [announce](https:\/\/www.nytimes.com\/2021\/01\/13\/business\/chinese-vaccine-brazil-sinovac.html) that CoronaVac has an overall efficacy of just over 50 percent. Turkey authorizes the vaccine for emergency use.\n\n**Feb. 6** Sinovac announces that China has given CoronaVac [conditional approval](https:\/\/www.nytimes.com\/live\/2021\/02\/06\/world\/covid-19-coronavirus#china-approves-a-second-covid-19-vaccine-and-other-news-from-around-the-world).\n\n**March 13** China asks visa applicants to get [inoculated with Chinese-made coronavirus vaccines](https:\/\/www.nytimes.com\/2021\/03\/12\/world\/china-vaccines-hong-kong.html).\n\n**April 1** Sinovac [announces](https:\/\/www.businesswire.com\/news\/home\/20210401005993\/en\/Sinovac%C2%A0Announced-Buildup-of-Two-Billion-Annual-Capacity-of-Its-COVID-19-Vaccine) that its capacity has increased to 2 billion doses after completing a third production line.\n\nSources: National Center for Biotechnology Information; Science; The Lancet; Lynda Coughlan, University of Maryland School of Medicine; Jenna Guthmiller, University of Chicago.\n\n## Tracking the Coronavirus","meta_canonical":null}

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Meta Title	How the Sinovac Covid-19 Vaccine Works - The New York Times
Meta Description	Using inactivated coronaviruses to train the immune system.
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Boilerpipe Text	U.S.A. Close nav World Close nav Health Close nav The private Chinese company Sinovac developed a coronavirus vaccine called CoronaVac . The vaccine is approved for use in China and authorized for emergency use in more than a dozen other countries. In a trial in Brazil, researchers found it had an efficacy against infections with or without symptoms of 50.65 percent . In a trial in Turkey, researchers found it had an efficacy of 91.25 percent against Covid-19 infections with symptoms. A Vaccine Made From Coronaviruses CoronaVac works by teaching the immune system to make antibodies against the SARS-CoV-2 coronavirus. The antibodies attach to viral proteins, such as the so-called spike proteins that stud its surface . To create CoronaVac, the Sinovac researchers started by obtaining samples of the coronavirus from patients in China, Britain, Italy, Spain and Switzerland. One sample from China eventually served as the basis for the vaccine. Killing the Virus The researchers grew large stocks of the coronavirus in monkey kidney cells. Then they doused the viruses with a chemical called beta-propiolactone. The compound disabled the coronaviruses by bonding to their genes. The inactivated coronaviruses could no longer replicate. But their proteins, including spike, remained intact. The researchers then drew off the inactivated viruses and mixed them with a tiny amount of an aluminum-based compound called an adjuvant. Adjuvants stimulate the immune system to boost its response to a vaccine. Inactivated viruses have been used for over a century. Jonas Salk used them to create his polio vaccine in the 1950s, and they’re the bases for vaccines against other diseases including rabies and hepatitis A . Prompting an Immune Response Because the coronaviruses in CoronaVac are dead, they can be injected into the arm without causing Covid-19. Once inside the body, some of the inactivated viruses are swallowed up by a type of immune cell called an antigen-presenting cell. The antigen-presenting cell tears the coronavirus apart and displays some of its fragments on its surface. A so-called helper T cell may detect the fragment. If the fragment fits into one of its surface proteins, the T cell becomes activated and can help recruit other immune cells to respond to the vaccine. Making Antibodies Another type of immune cell, called a B cell, may also encounter the inactivated coronavirus. B cells have surface proteins in a huge variety of shapes, and a few might have the right shape to latch onto the coronavirus. When a B cell locks on, it can pull part or all of the virus inside and present coronavirus fragments on its surface. A helper T cell activated against the coronavirus can latch onto the same fragment. When that happens, the B cell gets activated, too. It proliferates and pours out antibodies that have the same shape as their surface proteins. Stopping the Virus Once vaccinated with CoronaVac, the immune system can respond to an infection of live coronaviruses. B cells produce antibodies that stick to the invaders. Antibodies that target the spike protein can prevent the virus from entering cells. Other kinds of antibodies may block the virus by other means. Remembering the Virus While CoronaVac can offer some protection against Covid-19, no one can yet say how long that protection lasts. It’s possible that the level of antibodies drops over the course of months. But the immune system also contains special cells called memory B cells that might retain information about the coronavirus for years or even decades. Vaccine Timeline January, 2020 Sinovac begins developing an inactivated vaccine against the coronavirus. Sinovac engineers working with monkey kidney cells. Nicolas Asfouri/Agence France-Presse June Phase 1/2 trials on 743 volunteers find no severe adverse effects . July Sinovac launches a Phase 3 trial in Brazil, followed by others in Indonesia and Turkey . Reuters reports that the Chinese government gave the Sinovac vaccine emergency approval for limited use. A dose of CoronaVac in Turkey. Emrah Gurel/Associated Press October Authorities in the eastern Chinese city of Jiaxing announce they are giving CoronaVac to people in relatively high-risk jobs, including medical workers, port inspectors and public service personnel. Oct. 19 Officials in Brazil say that Sinovac is the safest of five vaccines they are testing in Phase 3 trials. November Sinovac publishes the details of its Phase 1/2 trial in a medical journal, showing a comparatively modest production of antibodies. Only a Phase 3 trial will demonstrate if that is enough to protect people from Covid-19. Nov. 19 The Brazilian government announces that they paused the country’s Sinovac trial the previous month because of an adverse event. The details of the pause were murky, raising suspicions that politics were involved. Two days after the announcement, the trial was allowed to resume . The Brazilian trial has recorded enough cases of Covid-19 to let researchers determine Sinovac’s efficacy. They expect to release their results by Dec. 23. Officials in Brazil hold boxes from a shipment of the vaccine. Alexandre Schneider/Getty Images December Sinovac says it expects to manufacture 300 million doses in 2020 and increase capacity to an annual production of 600 million doses. Dec. 23 Brazilian researchers announce that CoronaVac has an efficacy of over 50 percent . Dec. 24 Turkish officials announce that the vaccine has an efficacy rate of 91.25 percent . Jan. 7, 2021 Researchers in Brazil announce that CoronaVac has an efficacy of 78 percent. None of the vaccinated volunteers in their Phase 3 trial developed severe or moderate cases of Covid-19. But the efficacy estimate was based on the vaccine’s performance in a subgroup of volunteers. The overall efficacy is not formally released. Jan. 11 Indonesia authorizes the vaccine for emergency use. Jan. 13 Researchers in Brazil announce that CoronaVac has an overall efficacy of just over 50 percent. Turkey authorizes the vaccine for emergency use. Feb. 6 Sinovac announces that China has given CoronaVac conditional approval . March 13 China asks visa applicants to get inoculated with Chinese-made coronavirus vaccines . April 1 Sinovac announces that its capacity has increased to 2 billion doses after completing a third production line. Sources: National Center for Biotechnology Information; Science; The Lancet; Lynda Coughlan, University of Maryland School of Medicine; Jenna Guthmiller, University of Chicago. Tracking the Coronavirus
Markdown	[Skip to content](https://www.nytimes.com/interactive/2020/health/sinovac-covid-19-vaccine.html#site-content)[Skip to site index](https://www.nytimes.com/interactive/2020/health/sinovac-covid-19-vaccine.html#site-index) Search & Section Navigation Section Navigation Search [Health](https://www.nytimes.com/section/health) [Log in](https://myaccount.nytimes.com/auth/login?response_type=cookie&client_id=vi&redirect_uri=https%3A%2F%2Fwww.nytimes.com%2Fsubscription%2Fonboarding-offer%3FcampaignId%3D7JFJX%26EXIT_URI%3Dhttps%253A%252F%252Fwww.nytimes.com%252Finteractive%252F2020%252Fhealth%252Fsinovac-covid-19-vaccine.html&asset=masthead) [Today’s Paper](https://www.nytimes.com/section/todayspaper) [Health](https://www.nytimes.com/section/health)\\|How the Sinovac Vaccine Works https://nyti.ms/38xfqoT - Share full article - 0 # How the Sinovac Vaccine Works By [Jonathan Corum](https://www.nytimes.com/by/jonathan-corum) and [Carl Zimmer](https://www.nytimes.com/by/carl-zimmer)Updated May 7, 2021 [阅读简体中文版](https://cn.nytimes.com/health/20201229/sinovac-covid-19-vaccine/ "Read in Simplified Chinese")[閱讀繁體中文版](https://cn.nytimes.com/health/20201229/sinovac-covid-19-vaccine/zh-hant/ "Read in Traditional Chinese")[Leer en español](https://www.nytimes.com/es/interactive/2021/health/sinovac-vacuna-covid.html "Read in Spanish") - Share full article - 0 U.S.A. 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[Spain](https://www.nytimes.com/interactive/2021/world/spain-covid-cases.html) - [United Kingdom](https://www.nytimes.com/interactive/2021/world/united-kingdom-covid-cases.html) Health Close nav - [Vaccine Development](https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html) - [Coronavirus Variants](https://www.nytimes.com/interactive/2021/health/coronavirus-variant-tracker.html) - [Treatments](https://www.nytimes.com/interactive/2020/science/coronavirus-drugs-treatments.html) - [Answers to Your Covid-19 Questions](https://www.nytimes.com/interactive/2020/world/coronavirus-tips-advice.html) - [How the Covid-19 Vaccines Work](https://www.nytimes.com/interactive/2021/health/how-covid-19-vaccines-work.html) - [Symptoms of Covid-19](https://www.nytimes.com/interactive/2020/08/05/well/covid-19-symptoms.html) - [What Happens in an Infection](https://www.nytimes.com/interactive/2020/10/02/science/charting-a-coronavirus-infection.html) - [How Masks Work](https://www.nytimes.com/interactive/2020/10/30/science/wear-mask-covid-particles-ul.html) ![](https://static01.nyt.com/newsgraphics/2020/12/05/how-coronavirus-vaccines-work/223b8183b7e9cde2b16745b6f17504082c328540/1-syringe-sinovac-450.png) ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) The private Chinese company Sinovac developed a [coronavirus vaccine](https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html#sinovac) called CoronaVac. The vaccine is approved for use in China and authorized for emergency use in more than a dozen other countries. In a trial in Brazil, researchers found it had an efficacy against infections with or without symptoms of [50\.65 percent](https://www.nytimes.com/2021/01/13/business/chinese-vaccine-brazil-sinovac.html). In a trial in Turkey, researchers found it had an efficacy of 91.25 percent against Covid-19 infections with symptoms. ## A Vaccine Made From Coronaviruses CoronaVac works by teaching the immune system to make antibodies against the SARS-CoV-2 coronavirus. The antibodies attach to viral proteins, such as the so-called spike proteins that [stud its surface](https://www.nytimes.com/interactive/2020/health/coronavirus-unveiled.html). ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) Spikes Spike protein gene ![](https://static01.nyt.com/newsgraphics/2020/12/05/how-coronavirus-vaccines-work/223b8183b7e9cde2b16745b6f17504082c328540/2-virion-600.png) Spikes Spike protein gene CORONAVIRUS To create CoronaVac, the Sinovac researchers started by obtaining samples of the coronavirus from patients in China, Britain, Italy, Spain and Switzerland. One sample from China eventually served as the basis for the vaccine. ## Killing the Virus The researchers grew large stocks of the coronavirus in monkey kidney cells. Then they doused the viruses with a chemical called beta-propiolactone. The compound disabled the coronaviruses by bonding to their genes. The inactivated coronaviruses could no longer replicate. But their proteins, including spike, remained intact. ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) Inactivated genes Beta- propiolactone ![](https://static01.nyt.com/newsgraphics/2020/12/05/how-coronavirus-vaccines-work/223b8183b7e9cde2b16745b6f17504082c328540/2-virion-sinovac-600.png) Beta- propiolactone INACTIVATED CORONAVIRUS Inactivated genes The researchers then drew off the inactivated viruses and mixed them with a tiny amount of an aluminum-based compound called an adjuvant. Adjuvants stimulate the immune system to boost its response to a vaccine. Inactivated viruses have been used for over a century. Jonas Salk used them to create his [polio vaccine](https://www.nytimes.com/1955/04/13/archives/salk-polio-vaccine-proves-success-millions-will-be-immunized-soon.html) in the 1950s, and they’re the bases for vaccines against other diseases including [rabies](https://www.nytimes.com/1973/08/21/archives/vaccine-for-rabies-developed-cutting-shots-from-14-to-1-vaccine.html) and [hepatitis A](https://www.nytimes.com/1992/08/13/us/test-indicates-new-vaccine-works-against-hepatitis-a.html). ## Prompting an Immune Response Because the coronaviruses in CoronaVac are dead, they can be injected into the arm without causing Covid-19. Once inside the body, some of the inactivated viruses are swallowed up by a type of immune cell called an antigen-presenting cell. ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) Engulfing the virus Digesting proteins ANTIGEN- PRESENTING CELL Presenting virus protein fragments HELPER T CELL ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) INACTIVATED CORONAVIRUS Engulfing the virus ANTIGEN- PRESENTING CELL Digesting virus proteins Presenting virus protein fragments HELPER T CELL ![](https://static01.nyt.com/newsgraphics/2020/12/05/how-coronavirus-vaccines-work/223b8183b7e9cde2b16745b6f17504082c328540/5-apc-sinovac-600.png) INACTIVATED CORONAVIRUS Engulfing the virus ANTIGEN- PRESENTING CELL Digesting virus proteins Presenting virus protein fragments HELPER T CELL The antigen-presenting cell tears the coronavirus apart and displays some of its fragments on its surface. A so-called helper T cell may detect the fragment. If the fragment fits into one of its surface proteins, the T cell becomes activated and can help recruit other immune cells to respond to the vaccine. ## Making Antibodies Another type of immune cell, called a B cell, may also encounter the inactivated coronavirus. B cells have surface proteins in a huge variety of shapes, and a few might have the right shape to latch onto the coronavirus. When a B cell locks on, it can pull part or all of the virus inside and present coronavirus fragments on its surface. A helper T cell activated against the coronavirus can latch onto the same fragment. When that happens, the B cell gets activated, too. It proliferates and pours out antibodies that have the same shape as their surface proteins. ![](https://static01.nyt.com/newsgraphics/2020/12/05/how-coronavirus-vaccines-work/223b8183b7e9cde2b16745b6f17504082c328540/6-bcell-sinovac-900.png) ACTIVATED HELPER T CELL INACTIVATED CORONAVIRUS Activating the B cell Matching surface proteins B CELL SECRETED ANTIBODIES ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) ACTIVATED HELPER T CELL INACTIVATED CORONAVIRUS Activating the B cell Matching surface proteins B CELL SECRETED ANTIBODIES ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) ACTIVATED HELPER T CELL INACTIVATED CORONAVIRUS Activating the B cell Matching surface proteins B CELL SECRETED ANTIBODIES ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) ACTIVATED HELPER T CELL INACTIVATED CORONAVIRUS Activating the B cell Matching surface proteins B CELL SECRETED ANTIBODIES ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) ACTIVATED HELPER T CELL INACTIVATED CORONAVIRUS Activating the B cell Matching surface proteins B CELL SECRETED ANTIBODIES ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) ACTIVATED HELPER T CELL INACTIVATED CORONAVIRUS Activating the B cell Matching surface proteins B CELL SECRETED ANTIBODIES ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) ACTIVATED HELPER T CELL Activating the B cell B CELL Matching surface proteins INACTIVATED CORONAVIRUS ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) ACTIVATED HELPER T CELL Activating the B cell B CELL Matching surface proteins INACTIVATED CORONAVIRUS ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) ACTIVATED HELPER T CELL Activating the B cell B CELL Matching surface proteins INACTIVATED CORONAVIRUS ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) ACTIVATED HELPER T CELL Activating the B cell B CELL Matching surface proteins INACTIVATED CORONAVIRUS ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) ACTIVATED HELPER T CELL Activating the B cell B CELL Matching surface proteins INACTIVATED CORONAVIRUS ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) ACTIVATED HELPER T CELL Activating the B cell B CELL Matching surface proteins INACTIVATED CORONAVIRUS ## Stopping the Virus Once vaccinated with CoronaVac, the immune system can respond to an infection of live coronaviruses. B cells produce antibodies that stick to the invaders. Antibodies that target the spike protein can prevent the virus from entering cells. Other kinds of antibodies may block the virus by other means. ![](https://static01.nyt.com/newsgraphics/2020/12/05/how-coronavirus-vaccines-work/223b8183b7e9cde2b16745b6f17504082c328540/7-antibodies-sinovac-600.png) ANTIBODIES LIVE VIRUS ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) ANTIBODIES LIVE VIRUS ![](data:image/gif;base64,R0lGODlhCgAKAIAAAB8fHwAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw==) ANTIBODIES LIVE VIRUS ## Remembering the Virus While CoronaVac can offer some protection against Covid-19, no one can yet say how long that protection lasts. It’s possible that the level of antibodies drops over the course of months. But the immune system also contains special cells called memory B cells that might retain information about the coronavirus for years or even decades. ## Vaccine Timeline January, 2020 Sinovac begins developing an inactivated vaccine against the coronavirus. ![](https://static01.nyt.com/newsgraphics/2020/12/05/how-coronavirus-vaccines-work/assets/images/sinovac-cells-600.jpg) ![](https://static01.nyt.com/newsgraphics/2020/12/05/how-coronavirus-vaccines-work/assets/images/sinovac-cells-1050.jpg) Sinovac engineers working with monkey kidney cells.Nicolas Asfouri/Agence France-Presse June Phase 1/2 trials on 743 volunteers find [no severe adverse effects](https://www.medrxiv.org/content/10.1101/2020.07.31.20161216v1). July Sinovac launches a Phase 3 trial in Brazil, followed by others in [Indonesia](https://www.reuters.com/article/us-health-coronavirus-indonesia-vaccine/sinovac-launches-phase-3-trial-for-covid-19-vaccine-in-indonesia-reports-phase-2-details-idUSKCN2570E9) and [Turkey](http://www.sinovac.com/?optionid=754&auto_id=911). Reuters [reports](https://www.nytimes.com/reuters/2020/08/28/world/asia/28reuters-health-coronavirus-china-vaccines.html) that the Chinese government gave the Sinovac vaccine emergency approval for limited use. ![](https://static01.nyt.com/newsgraphics/2020/12/05/how-coronavirus-vaccines-work/assets/images/sinovac-syringe-600.jpg) ![](https://static01.nyt.com/newsgraphics/2020/12/05/how-coronavirus-vaccines-work/assets/images/sinovac-syringe-1050.jpg) A dose of CoronaVac in Turkey.Emrah Gurel/Associated Press October Authorities in the eastern Chinese city of Jiaxing announce they are [giving CoronaVac](https://www.nytimes.com/live/2020/10/16/world/covid-coronavirus/a-chinese-city-says-it-has-given-some-residents-a-vaccine-and-other-news-from-around-the-world) to people in relatively high-risk jobs, including medical workers, port inspectors and public service personnel. Oct. 19 Officials in Brazil [say](https://fortune.com/2020/10/20/covid-vaccine-china-brazil-testing-ground-safest-most-promising-sinovac/) that Sinovac is the safest of five vaccines they are testing in Phase 3 trials. November Sinovac [publishes](https://www.thelancet.com/journals/laninf/article/PIIS1473-3099$20$30843-4/fulltext) the details of its Phase 1/2 trial in a medical journal, showing a comparatively modest production of antibodies. Only a Phase 3 trial will demonstrate if that is enough to protect people from Covid-19. Nov. 19 The Brazilian government [announces](https://www.nytimes.com/2020/11/10/world/asia/brazil-china-vaccine-covid19.html) that they paused the country’s Sinovac trial the previous month because of an adverse event. The details of the pause were murky, raising suspicions that politics were involved. Two days after the announcement, the trial was [allowed to resume](https://www.nytimes.com/2020/11/11/world/brazil-resumes-chinese-vaccine-trial-after-a-brief-suspension-following-the-death-of-a-volunteer.html). The Brazilian trial has recorded enough cases of Covid-19 to let researchers determine Sinovac’s efficacy. They expect to release their results by Dec. 23. ![](https://static01.nyt.com/newsgraphics/2020/12/05/how-coronavirus-vaccines-work/assets/images/sinovac-brazil-600.jpg) ![](https://static01.nyt.com/newsgraphics/2020/12/05/how-coronavirus-vaccines-work/assets/images/sinovac-brazil-1050.jpg) Officials in Brazil hold boxes from a shipment of the vaccine.Alexandre Schneider/Getty Images December Sinovac [says](https://www.businesswire.com/news/home/20201206005056/en/Sinovac-Secures-Approximately-500-Million-in-Funding-for-COVID-19-Vaccine-Development) it expects to manufacture 300 million doses in 2020 and increase capacity to an annual production of 600 million doses. Dec. 23 Brazilian researchers announce that CoronaVac has an efficacy of [over 50 percent](https://www.reuters.com/article/us-health-coronavirus-sinovac-brazil/brazil-institute-says-coronavac-efficacy-above-50-but-delays-full-results-idUSKBN28X2CR). Dec. 24 Turkish officials announce that the vaccine has an efficacy rate of [91\.25 percent](https://www.nytimes.com/2020/12/25/health/turkey-brazil-sinovac-coronavirus-vaccine.html). Jan. 7, 2021 Researchers in Brazil [announce](https://www.nytimes.com/2021/01/07/business/china-coronavirus-vaccine-sinovac.html) that CoronaVac has an efficacy of 78 percent. None of the vaccinated volunteers in their Phase 3 trial developed severe or moderate cases of Covid-19. But the efficacy estimate was based on the vaccine’s performance in a subgroup of volunteers. The overall efficacy is not formally released. Jan. 11 [Indonesia](https://www.reuters.com/article/us-health-coronavirus-indonesia/indonesia-approves-chinas-sinovac-vaccine-as-infections-surge-idUSKBN29G0RP) authorizes the vaccine for emergency use. Jan. 13 Researchers in Brazil [announce](https://www.nytimes.com/2021/01/13/business/chinese-vaccine-brazil-sinovac.html) that CoronaVac has an overall efficacy of just over 50 percent. Turkey authorizes the vaccine for emergency use. Feb. 6 Sinovac announces that China has given CoronaVac [conditional approval](https://www.nytimes.com/live/2021/02/06/world/covid-19-coronavirus#china-approves-a-second-covid-19-vaccine-and-other-news-from-around-the-world). March 13 China asks visa applicants to get [inoculated with Chinese-made coronavirus vaccines](https://www.nytimes.com/2021/03/12/world/china-vaccines-hong-kong.html). April 1 Sinovac [announces](https://www.businesswire.com/news/home/20210401005993/en/Sinovac%C2%A0Announced-Buildup-of-Two-Billion-Annual-Capacity-of-Its-COVID-19-Vaccine) that its capacity has increased to 2 billion doses after completing a third production line. Sources: National Center for Biotechnology Information; Science; The Lancet; Lynda Coughlan, University of Maryland School of Medicine; Jenna Guthmiller, University of Chicago. ## Tracking the Coronavirus ### United States - [Latest Maps and Data Cases and deaths for every county](https://www.nytimes.com/interactive/2021/us/covid-cases.html) - [Vaccinations How many have been vaccinated, and who’s eligible](https://www.nytimes.com/interactive/2020/us/covid-19-vaccine-doses.html) - [Your Places Build your own dashboard to track cases](https://www.nytimes.com/interactive/2021/us/covid-cases-deaths-tracker.html) - [Hospitals Near You How many I.C.U. beds are occupied](https://www.nytimes.com/interactive/2020/us/covid-hospitals-near-you.html) ### World - [Latest Maps and Data Cases and deaths for every country](https://www.nytimes.com/interactive/2021/world/covid-cases.html) - [Global Vaccinations How many have been vaccinated, by country](https://www.nytimes.com/interactive/2021/world/covid-vaccinations-tracker.html) ### Health - 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Readable Markdown	U.S.A. Close nav World Close nav Health Close nav The private Chinese company Sinovac developed a [coronavirus vaccine](https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html#sinovac) called CoronaVac. The vaccine is approved for use in China and authorized for emergency use in more than a dozen other countries. In a trial in Brazil, researchers found it had an efficacy against infections with or without symptoms of [50\.65 percent](https://www.nytimes.com/2021/01/13/business/chinese-vaccine-brazil-sinovac.html). In a trial in Turkey, researchers found it had an efficacy of 91.25 percent against Covid-19 infections with symptoms. ## A Vaccine Made From Coronaviruses CoronaVac works by teaching the immune system to make antibodies against the SARS-CoV-2 coronavirus. The antibodies attach to viral proteins, such as the so-called spike proteins that [stud its surface](https://www.nytimes.com/interactive/2020/health/coronavirus-unveiled.html). To create CoronaVac, the Sinovac researchers started by obtaining samples of the coronavirus from patients in China, Britain, Italy, Spain and Switzerland. One sample from China eventually served as the basis for the vaccine. ## Killing the Virus The researchers grew large stocks of the coronavirus in monkey kidney cells. Then they doused the viruses with a chemical called beta-propiolactone. The compound disabled the coronaviruses by bonding to their genes. The inactivated coronaviruses could no longer replicate. But their proteins, including spike, remained intact. The researchers then drew off the inactivated viruses and mixed them with a tiny amount of an aluminum-based compound called an adjuvant. Adjuvants stimulate the immune system to boost its response to a vaccine. Inactivated viruses have been used for over a century. Jonas Salk used them to create his [polio vaccine](https://www.nytimes.com/1955/04/13/archives/salk-polio-vaccine-proves-success-millions-will-be-immunized-soon.html) in the 1950s, and they’re the bases for vaccines against other diseases including [rabies](https://www.nytimes.com/1973/08/21/archives/vaccine-for-rabies-developed-cutting-shots-from-14-to-1-vaccine.html) and [hepatitis A](https://www.nytimes.com/1992/08/13/us/test-indicates-new-vaccine-works-against-hepatitis-a.html). ## Prompting an Immune Response Because the coronaviruses in CoronaVac are dead, they can be injected into the arm without causing Covid-19. Once inside the body, some of the inactivated viruses are swallowed up by a type of immune cell called an antigen-presenting cell. The antigen-presenting cell tears the coronavirus apart and displays some of its fragments on its surface. A so-called helper T cell may detect the fragment. If the fragment fits into one of its surface proteins, the T cell becomes activated and can help recruit other immune cells to respond to the vaccine. ## Making Antibodies Another type of immune cell, called a B cell, may also encounter the inactivated coronavirus. B cells have surface proteins in a huge variety of shapes, and a few might have the right shape to latch onto the coronavirus. When a B cell locks on, it can pull part or all of the virus inside and present coronavirus fragments on its surface. A helper T cell activated against the coronavirus can latch onto the same fragment. When that happens, the B cell gets activated, too. It proliferates and pours out antibodies that have the same shape as their surface proteins. ## Stopping the Virus Once vaccinated with CoronaVac, the immune system can respond to an infection of live coronaviruses. B cells produce antibodies that stick to the invaders. Antibodies that target the spike protein can prevent the virus from entering cells. Other kinds of antibodies may block the virus by other means. ## Remembering the Virus While CoronaVac can offer some protection against Covid-19, no one can yet say how long that protection lasts. It’s possible that the level of antibodies drops over the course of months. But the immune system also contains special cells called memory B cells that might retain information about the coronavirus for years or even decades. ## Vaccine Timeline January, 2020 Sinovac begins developing an inactivated vaccine against the coronavirus. ![](https://static01.nyt.com/newsgraphics/2020/12/05/how-coronavirus-vaccines-work/assets/images/sinovac-cells-1050.jpg) Sinovac engineers working with monkey kidney cells.Nicolas Asfouri/Agence France-Presse June Phase 1/2 trials on 743 volunteers find [no severe adverse effects](https://www.medrxiv.org/content/10.1101/2020.07.31.20161216v1). July Sinovac launches a Phase 3 trial in Brazil, followed by others in [Indonesia](https://www.reuters.com/article/us-health-coronavirus-indonesia-vaccine/sinovac-launches-phase-3-trial-for-covid-19-vaccine-in-indonesia-reports-phase-2-details-idUSKCN2570E9) and [Turkey](http://www.sinovac.com/?optionid=754&auto_id=911). Reuters [reports](https://www.nytimes.com/reuters/2020/08/28/world/asia/28reuters-health-coronavirus-china-vaccines.html) that the Chinese government gave the Sinovac vaccine emergency approval for limited use. ![](https://static01.nyt.com/newsgraphics/2020/12/05/how-coronavirus-vaccines-work/assets/images/sinovac-syringe-1050.jpg) A dose of CoronaVac in Turkey.Emrah Gurel/Associated Press October Authorities in the eastern Chinese city of Jiaxing announce they are [giving CoronaVac](https://www.nytimes.com/live/2020/10/16/world/covid-coronavirus/a-chinese-city-says-it-has-given-some-residents-a-vaccine-and-other-news-from-around-the-world) to people in relatively high-risk jobs, including medical workers, port inspectors and public service personnel. Oct. 19 Officials in Brazil [say](https://fortune.com/2020/10/20/covid-vaccine-china-brazil-testing-ground-safest-most-promising-sinovac/) that Sinovac is the safest of five vaccines they are testing in Phase 3 trials. November Sinovac [publishes](https://www.thelancet.com/journals/laninf/article/PIIS1473-3099$20$30843-4/fulltext) the details of its Phase 1/2 trial in a medical journal, showing a comparatively modest production of antibodies. Only a Phase 3 trial will demonstrate if that is enough to protect people from Covid-19. Nov. 19 The Brazilian government [announces](https://www.nytimes.com/2020/11/10/world/asia/brazil-china-vaccine-covid19.html) that they paused the country’s Sinovac trial the previous month because of an adverse event. The details of the pause were murky, raising suspicions that politics were involved. Two days after the announcement, the trial was [allowed to resume](https://www.nytimes.com/2020/11/11/world/brazil-resumes-chinese-vaccine-trial-after-a-brief-suspension-following-the-death-of-a-volunteer.html). The Brazilian trial has recorded enough cases of Covid-19 to let researchers determine Sinovac’s efficacy. They expect to release their results by Dec. 23. ![](https://static01.nyt.com/newsgraphics/2020/12/05/how-coronavirus-vaccines-work/assets/images/sinovac-brazil-1050.jpg) Officials in Brazil hold boxes from a shipment of the vaccine.Alexandre Schneider/Getty Images December Sinovac [says](https://www.businesswire.com/news/home/20201206005056/en/Sinovac-Secures-Approximately-500-Million-in-Funding-for-COVID-19-Vaccine-Development) it expects to manufacture 300 million doses in 2020 and increase capacity to an annual production of 600 million doses. Dec. 23 Brazilian researchers announce that CoronaVac has an efficacy of [over 50 percent](https://www.reuters.com/article/us-health-coronavirus-sinovac-brazil/brazil-institute-says-coronavac-efficacy-above-50-but-delays-full-results-idUSKBN28X2CR). Dec. 24 Turkish officials announce that the vaccine has an efficacy rate of [91\.25 percent](https://www.nytimes.com/2020/12/25/health/turkey-brazil-sinovac-coronavirus-vaccine.html). Jan. 7, 2021 Researchers in Brazil [announce](https://www.nytimes.com/2021/01/07/business/china-coronavirus-vaccine-sinovac.html) that CoronaVac has an efficacy of 78 percent. None of the vaccinated volunteers in their Phase 3 trial developed severe or moderate cases of Covid-19. But the efficacy estimate was based on the vaccine’s performance in a subgroup of volunteers. The overall efficacy is not formally released. Jan. 11 [Indonesia](https://www.reuters.com/article/us-health-coronavirus-indonesia/indonesia-approves-chinas-sinovac-vaccine-as-infections-surge-idUSKBN29G0RP) authorizes the vaccine for emergency use. Jan. 13 Researchers in Brazil [announce](https://www.nytimes.com/2021/01/13/business/chinese-vaccine-brazil-sinovac.html) that CoronaVac has an overall efficacy of just over 50 percent. Turkey authorizes the vaccine for emergency use. Feb. 6 Sinovac announces that China has given CoronaVac [conditional approval](https://www.nytimes.com/live/2021/02/06/world/covid-19-coronavirus#china-approves-a-second-covid-19-vaccine-and-other-news-from-around-the-world). March 13 China asks visa applicants to get [inoculated with Chinese-made coronavirus vaccines](https://www.nytimes.com/2021/03/12/world/china-vaccines-hong-kong.html). April 1 Sinovac [announces](https://www.businesswire.com/news/home/20210401005993/en/Sinovac%C2%A0Announced-Buildup-of-Two-Billion-Annual-Capacity-of-Its-COVID-19-Vaccine) that its capacity has increased to 2 billion doses after completing a third production line. Sources: National Center for Biotechnology Information; Science; The Lancet; Lynda Coughlan, University of Maryland School of Medicine; Jenna Guthmiller, University of Chicago. ## Tracking the Coronavirus
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