On the same day that the Centers for Disease Control and Prevention eased COVID-19 guidelines, the Food and Drug Administration issued a statement warning that at-home rapid antigen tests can give false negative results and people who Those who require testing should plan to do so more than once to ensure they are not “unknowingly spreading the SARS-CoV-2 virus to others”.
Health experts recommend testing for people who have been exposed to the virus or are showing symptoms.
“Today’s recommendations are based on the latest study results from people with likely Omicron infection, showing that repeat testing after a negative at-home COVID-19 antigen test result increases the chance of an accurate result,” the FDA said in a safety notice released on Thursday.
Previously, the FDA advised people to have two rapid antigen tests for two or three days to rule out infection.
These recommendations, the FDA says, are based on data from a comprehensive study conducted in collaboration with the National Institutes of Health (NIH) and the University of Massachusetts Chan Medical School, which showed that this testing method repeatedly reduced the risk of negative results . More than 7,000 participants are said to have taken part in the study.
In the warning, the agency said antigen testing, also known as at-home COVID-19 testing, is less accurate than molecular testing, such as B. Polymerase chain reaction tests (PCR). This means that testing at home too soon after exposure to COVID-19 can result in a false-negative result, especially if a person has no symptoms.
The FDA now recommends that people who want to do tests at home get several of them so they can test more than once. For people with COVID-19 symptoms who test at home and get a negative result, the agency recommends taking a second home COVID-19 test 48 hours after the first, for a minimum of two tests total.
“If you get a negative result on the second test and are concerned you may have COVID-19, you can choose to test again 48 hours after the second test, consider a molecular-based lab test, or call your provider,” said the FDA.
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For those who suspect COVID-19 exposure but have no symptoms, the FDA now recommends up to three tests, each separated by a 48-hour period.
If a person tests positive at home, initially or after repeat testing, the agency emphasized that it likely means a person has COVID-19 and they “should follow CDC guidelines for people with COVID-19.”
Health experts warn that testing too soon can lead to false negative results. For those who have been exposed to COVID-19, the Centers for Disease Control and Prevention recommends waiting at least five days after exposure to COVID-19 before having an antigen test. This is because it can take several days for these home tests to detect an infection.
The FDA also said people don’t have to stick to a specific brand of test and can use tests from different manufacturers for this repeated testing approach each time. For a list of all FDA-approved home tests and more information on at-home testing for COVID-19, click here.