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| URL | https://coronavirus.jhu.edu/testing/testing-faq/facts-viral-and-serology-tests | ||||||||||||||||||
| Last Crawled | 2026-03-23 02:33:43 (1 month ago) | ||||||||||||||||||
| First Indexed | 2020-05-19 00:04:04 (5 years ago) | ||||||||||||||||||
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| Content | |||||||||||||||||||
| Meta Title | Testing FAQ - Johns Hopkins Coronavirus Resource Center | ||||||||||||||||||
| Meta Description | These FAQs provide answers to some of the most frequently asked questions COVID-19 | ||||||||||||||||||
| Meta Canonical | edu,jhu!coronavirus,/testing/testing-faq s443 | ||||||||||||||||||
| Boilerpipe Text | What is the test?
Viral Test:
A viral test is an oral or nasal swab or saliva test that looks for
evidence of an active viral infection
. There are two major types: a PCR test and an antigen test.
Serology Test:
A serology test is a blood test that looks for
evidence of someone’s prior infection
with the virus.
What does the test do?
Viral Test:
PCR tests look for the
presence of a virus’s genetic material
, while antigen tests look for
specific proteins on a virus’s surface
. Antigen tests produce results more quickly, but may be less sensitive.
Serology Test:
The test provides evidence that someone may have been exposed to the virus in the past, potentially even if they did not have symptoms, by
detecting antibodies specific to the virus
.
What doesn't the test do?
Viral Test:
Viral tests do not indicate
whether someone was infected in the past
.
Serology Test:
The test does not
diagnose an active infection or identify who is protected from reinfection
(antibodies have not been proven to guarantee immunity).
How does the FDA handle the test?
Viral Test:
The FDA formally
evaluates these tests prior to use
.
Serology Test:
The FDA
does not formally evaluate these tests prior to use
, though a few have Emergency Use Authorization. | ||||||||||||||||||
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Testing Hub
# Testing FAQ
### These FAQs provide answers to some of the most frequently asked questions on COVID-19
Share
[Overview](https://coronavirus.jhu.edu/testing/testing-faq/overview)[Facts: Viral and Serology Tests](https://coronavirus.jhu.edu/testing/testing-faq/facts-viral-and-serology-tests)
### The Facts About COVID-19 Tests
COVID-19 tests are critical to measuring the spread of the disease and determining how to handle the pandemic. The two types of COVID-19 test – serology tests and viral tests – serve different purposes and have different limitations.
**Knowing the facts about these tests is essential to making decisions that are best for the public’s health.**
[Created with Sketch.Download PDF](https://coronavirus.jhu.edu/downloads/JHU_Facts_About_COVID-19_tests.pdf)
## The Two Test Types
Question
Viral Test
Serology Test
What is the test?
###### Viral Test:
A viral test is an oral or nasal swab or saliva test that looks for **evidence of an active viral infection**. There are two major types: a PCR test and an antigen test.
###### Serology Test:
A serology test is a blood test that looks for **evidence of someone’s prior infection** with the virus.
What does the test do?
###### Viral Test:
PCR tests look for the **presence of a virus’s genetic material**, while antigen tests look for **specific proteins on a virus’s surface**. Antigen tests produce results more quickly, but may be less sensitive.
###### Serology Test:
The test provides evidence that someone may have been exposed to the virus in the past, potentially even if they did not have symptoms, by **detecting antibodies specific to the virus**.
What doesn't the test do?
###### Viral Test:
Viral tests do not indicate **whether someone was infected in the past**.
###### Serology Test:
The test does not **diagnose an active infection or identify who is protected from reinfection** (antibodies have not been proven to guarantee immunity).
How does the FDA handle the test?
###### Viral Test:
The FDA formally **evaluates these tests prior to use**.
###### Serology Test:
The FDA **does not formally evaluate these tests prior to use**, though a few have Emergency Use Authorization.
[](https://coronavirus.jhu.edu/)
**Johns Hopkins experts in global public health, infectious disease, and emergency preparedness have been at the forefront of the international response to COVID-19.**
This website is a resource to help advance the understanding of the virus, inform the public, and brief policymakers in order to guide a response, improve care, and save lives.
This Project is supported by [Bloomberg Philanthropies](https://www.bloomberg.org/) and the [Stavros Niarchos Foundation (SNF)](https://www.snf.org/).
[](https://www.bloomberg.org/)[](https://www.snf.org/)
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### Vaccines
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### Pandemic Data Initiative
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### By Region
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### Events & News
- [Webcasts & Videos](https://coronavirus.jhu.edu/live)
- [30-Minute COVID-19 Briefing](https://coronavirus.jhu.edu/live/events/covid-19-briefing-expert-insights)
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### About
- [About Us](https://coronavirus.jhu.edu/about)
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JHU.edu Copyright © 2026 by Johns Hopkins University & Medicine. All rights reserved. | ||||||||||||||||||
| Readable Markdown | What is the test?
###### Viral Test:
A viral test is an oral or nasal swab or saliva test that looks for **evidence of an active viral infection**. There are two major types: a PCR test and an antigen test.
###### Serology Test:
A serology test is a blood test that looks for **evidence of someone’s prior infection** with the virus.
What does the test do?
###### Viral Test:
PCR tests look for the **presence of a virus’s genetic material**, while antigen tests look for **specific proteins on a virus’s surface**. Antigen tests produce results more quickly, but may be less sensitive.
###### Serology Test:
The test provides evidence that someone may have been exposed to the virus in the past, potentially even if they did not have symptoms, by **detecting antibodies specific to the virus**.
What doesn't the test do?
###### Viral Test:
Viral tests do not indicate **whether someone was infected in the past**.
###### Serology Test:
The test does not **diagnose an active infection or identify who is protected from reinfection** (antibodies have not been proven to guarantee immunity).
How does the FDA handle the test?
###### Viral Test:
The FDA formally **evaluates these tests prior to use**.
###### Serology Test:
The FDA **does not formally evaluate these tests prior to use**, though a few have Emergency Use Authorization. | ||||||||||||||||||
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