Key takeaways:
Some newer COVID variants are more likely to be found in the saliva and mouth than previous variants. This has led to questions about the most accurate way to test for the virus.
Rapid home tests aren’t designed to collect a throat swab. They’re only validated to give accurate results from nasal swabs.
Rapid tests may give false results from a throat swab. So, for rapid home tests, experts recommend doing nasal swabs.
When the Omicron variant emerged, researchers found that it was more concentrated in the mouth and upper respiratory tract than other variants. This led to questions about the best way to perform rapid at-home tests for COVID.
Is a nasal swab good enough, or is it more accurate to swab the throat? Or is it better to combine nasal and throat swabs? The answer is a bit complicated. We’ll discuss the differences between COVID tests and what the current evidence says about combined nasal and throat testing.
The key difference between nasal and throat swabs is the bodily fluid that the tests collect. Each collection method checks for the virus that causes COVID in a different location of the upper respiratory tract (nose, throat, and mouth). And many tests are designed to collect from only one location.
There are different ways to test for COVID:
Nasal swabs are generally self-administered, either in your home or at testing sites that let you swab yourself.
Throat swabs (oropharyngeal swabs) collect a sample from the back of the throat by going through the mouth. Usually a healthcare provider does this.
Nasopharyngeal swabs go deeper into the nose and collect a sample from the back of the nose or back of the throat. Usually a medical provider performs this swab.
Saliva samples use saliva to test for the COVID virus. This is usually done by spitting into a tube to collect a saliva specimen.
The rapid antigen tests that most people use in the U.S. are specifically designed for nasal swabs.
The pros of a throat swab include:
Comfort: For some people, it’s more comfortable to swab their throat than their nose.
Location: If a particular variant is more concentrated in someone’s throat, swabbing there could have a higher chance of a positive test. But this is not proven yet.
The cons of a throat swab include:
Uncertain accuracy of results: Current at-home COVID tests are only valid with a nasal swab. This means that the tests have not been verified with throat swabbing. So it is not known if they will work correctly with a throat swab sample.
Difficulty getting a good sample: Getting a good throat swab sample means swabbing the back of your throat thoroughly for a few seconds. This can be hard to do, especially if you have a strong gag reflex.
The FDA recommends against swabbing your throat with the current home COVID tests for the reasons above. This type of sample should only be collected by a healthcare provider.
The pros of a nasal swab include:
Recommended: The FDA recommends swabbing your nose with home COVID tests (not your throat).
Better accuracy: Home tests were designed to be used in the nose. So the results are more trustworthy.
The cons of a nasal swab include:
Discomfort: Many people find swabbing their nose uncomfortable.
Location: Since a nasal swab gets a sample from your nose, it won't pick up a virus that's only in the throat. But this is still debated.
There’s ongoing research to find the most accurate way to test for COVID. New variants make this a challenge. For example, the Omicron variant tends to stay in the upper respiratory tract, rather than travel to the lower respiratory tract or lungs. So a throat swab may be more likely to find it. But again, the research is still in progress.
One study suggests that saliva swabs may be more accurate to detect the Omicron variant when compared to nasal swabs. But this study looked at PCR tests, not rapid tests that are done at home. So the results may not apply to home testing because these tests work differently. Another study found that PCR throat swabs were just slightly better than nasal swabs in detecting the virus. But this study was done before the Omicron variant.
Again, throat swabs are more difficult to collect. And if done incorrectly, the result may not be accurate. At this time, if testing at home, it’s best to use a nasal swab.
There’s limited evidence that supports combining throat and nasal swabs with rapid tests. And this is mostly based on personal accounts. There have been multiple social media stories of people who test positive on a throat swab after a negative result from a nasal swab. But solid, scientific research about these claims is still in the works.
Currently, rapid home tests in the U.S. aren’t designed to test the throat. And this is related to the pH of a saliva sample.
Research shows that when the pH of the sample changes, a rapid COVID test can produce a false-positive result. In fact, even drinking acidic juices or soda close to when you collect a sample can affect the result of a rapid test. And the pH of the mouth is naturally more acidic than the nose. So the FDA does not recommend combining tests at home until more research is done.
Saliva testing — and possibly throat swabs — may be more accurate for the Omicron variant than nasal swabs. But rapid home tests aren’t designed for throat swabs. To avoid a potentially false result, only use these tests as intended. Until there’s more research, we can’t know for sure if combination swabs with home tests are a good idea. When in doubt, consider a PCR test to get a more accurate result.
American Society for Microbiology. (2021). Avoiding false positive for SARS-CoV-2 when using rapid antigen tests.
HKUMed. (2021). HKUMed finds Omicron SARS-CoV-2 can infect faster and better than Delta in human bronchus but with less severe infection in lung.
Lee, R. A., et al. (2021). Performance of saliva, oropharyngeal swabs, and nasal swabs for SARS-CoV-2 molecular detection: A systematic review and meta-analysis. Journal of Clinical Microbiology.
Marais, G., et al. (2022). Improved oral detection is a characteristic of Omicron infection and has implications for clinical sampling and tissue tropism. Journal of Clinical Virology.
Rubin, R. (2023). Swab the throat as well as the nose? The debate over the best way to test for SARS-CoV-2. Journal of the American Medical Association.
U.S. Food and Drug Administration [@US_FDA]. (2022). Please don’t go sticking that #COVID19 testing swab down your throat. Use swabs as instructed: via the nose [Tweet]. X.
U.S. Food and Drug Administration. (2023). COVID-19 test basics.