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Jan 21, 2022
5 min read

Which COVID tests are the most accurate?

Making sure to get an accurate COVID test is important. Some tests are more accurate than others, but that’s not always a good thing. We’ll explain everything you need to know about how accurate COVID tests really are, and what you should do with your results.

Important

Information about the novel coronavirus (the virus that causes COVID-19) is constantly evolving. We will refresh our novel coronavirus content periodically based on newly published peer-reviewed findings to which we have access. For the most reliable and up-to-date information, please visit the CDC website or the WHO’s advice for the public.

If you’re having symptoms or you’ve been exposed to someone with COVID, you want to know you’re taking a COVID test that will give you an accurate result. With so many options on the market, though, how do you know which COVID test is the most accurate? Keep reading to learn more. 

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Which COVID test is the most accurate? 

Typically, the most accurate COVID tests are the PCR tests. But they’re not always the best choice.

Overall, the PCR test does a great job identifying people who are infected with the coronavirus, making it highly sensitive. And while they have near-perfect accuracy in a laboratory setting, PCR tests are about 80% sensitive in real life, meaning they catch eight out of every ten cases of coronavirus (Yohe, n.d.). But that means that two out of ten people with COVID may go back to their day-to-day, not realizing that they have the virus. 

Because no test is 100% accurate all of the time, most healthcare providers will use other information—like potential exposure, symptoms, and how high-risk someone is—when interpreting your test results. 

While PCR is very good at detecting the coronavirus, the technique is more expensive and takes longer than the rapid antigen tests. Also, PCR tests require special machinery that isn’t available everywhere. Samples often need to be sent to laboratories with expensive PCR machines, which can take hours or even days before you get your results. 

With different variants taking over, there were questions as to whether the tests we have available were as good at detecting the slightly altered virus. The answer seems to be mixed. In one study, researchers in Australia found that ten commercially-available antigen tests were just as good, if not better, at detecting the Omicron variant as the Delta variant (Deerain, 2021).

And while there was some buzz around the fact that collecting your sample from a throat swab rather than a nasal swab might help detect Omicron more effectively, researchers at UCSF disagree. Their early study results, which have yet to be peer-reviewed, showed that nasal swabbing was far more effective at detecting Omicron than throat swabs. They found that throat swabs were about half as sensitive when it came to finding the virus, so it doesn’t seem that this method will replace the standard nasal swab guidelines (Schrom, 2022). 

Rapid antigen tests are not as accurate as PCR testing, but they can be performed faster and are relatively inexpensive. But if the virus isn’t present in your sample, or it’s early in the course of infection, the test may be negative when you have COVID. 

If you have an inconclusive or negative antigen test and have symptoms of COVID, the Centers for Disease Control and Prevention (CDC) recommends getting a PCR test to confirm the results. You should quarantine while waiting for your results (CDC, 2021). 

And while antigen tests aren’t as good at catching every single case of COVID, that’s not always such a bad thing. Researchers have found that those super-accurate PCR tests remain positive for up to three months after people have recovered from COVID and are no longer infectious, meaning they’re not a good option in deciding whether or not you still need to stay home (Mina, 2020). 

That’s where rapid tests come in. With increased availability and the sheer joy of doing your test yourself in the comfort of your own home, rapid tests are a great way to keep on top of local outbreaks. 

But as with all tests, take your results with a grain of salt. There’s a concept in the world of medicine called “pretest probability.” It’s a fancy way of saying that you need to look at the whole picture. For example, if you live in a household with four other people and they have all tested positive for COVID, and you yourself begin to experience symptoms, you might take a COVID test and the result of that test might be negative. But in this case and with all the factors coming into play, that result likely is not accurate. 

When the Omicron variant descended upon us and widespread infection and testing picked up once again, it became clear that getting accessible, accurate COVID tests was crucial. And while PCR tests are somewhat more precise than rapid tests, access is an undeniably essential element when it comes to controlling the spread of the virus. 

What about antibody testing? 

Antibody tests look for your body’s response to the virus or vaccine. Each test is different and the nuances can be a little complicated to understand, but overall, these tests can tell you if you have recently had the coronavirus or have been vaccinated against COVID-19. 

Antibody tests won’t tell you if you are currently infected with the virus, and they aren’t a proxy for protection from the virus. That’s because there are many types of antibodies, and researchers have yet to establish a threshold at which a person is protected from future infection (CDC, 2021). Also, antibody levels can drop within a few months even though a person still has protection from the virus. 

Still, most of the available antibody tests are great at finding antibodies, so if you’re curious, say, about whether your unvaccinated toddler had COVID a month ago, these should be able to tell you. Keep in mind that unlike PCR and rapid tests, antibody tests require a blood sample.

Overall, most of the COVID tests that the FDA has approved are pretty good at finding out if you have COVID or not. PCR tests are usually considered the most accurate. While they were developed to catch every single case of COVID, it doesn’t hold true in real life. All kinds of factors can make these tests less accurate, including improper collection, contamination with other samples, and more. 

References

  1. Centers for Disease Control and Prevention (CDC). (2021, August 2). Interim Guidance for Antigen Testing for SARS-CoV-2. Retrieved on Jan. 13, 2021 from https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/testing.html
  2. Deerain, J., Druce, J., Tran, T., Batty, M., Yoga, Y., Fennell, M., et al. (2021). Assessment of the analytical sensitivity of ten lateral flow devices against the SARS-CoV-2 omicron variant. Journal of Clinical Microbiology, jcm0247921. Advance online publication. doi: 10.1128/jcm.02479-21. Retrieved from https://pubmed.ncbi.nlm.nih.gov/34936477/
  3. Mina, M. J., Parker, R., & Larremore, D. B. (2020). Rethinking Covid-19 Test Sensitivity – A Strategy for Containment. The New England journal of medicine, 383(22), e120. Retrieved from https://www.nejm.org/doi/10.1056/NEJMp2025631
  4. Schrom, J., Marquez, C., Pilarowski, G., Wang, G., Mitchell, A., & Puccinelli, R., et al. (2022). Direct comparison of SARS-COV-2 nasal RT-PCR and rapid antigen test (binaxnow™) at a community testing site during an Omicron Surge. MedRxIV. Pre-print. Retrieved from https://www.medrxiv.org/content/10.1101/2022.01.08.22268954v4 
  5. Yohe, S., MD. (n.d.). How Good are COVID-19 (SARS-CoV-2) Diagnostic PCR Tests? CAP: College of American Pathologists. Retrieved on Jan. 9, 2021 from https://www.cap.org/member-resources/articles/how-good-are-covid-19-sars-cov-2-diagnostic-pcr-tests#:~:text=The%20analytic%20performance%20of%20PCR,specificity%20is%20near%20100%25%20also