By Kathleen Doheny
This might be a good time to stock up on home COVID-19 tests.
Today, the FDA issued new guidance on at-home COVID testing. It still recommends repeating the test after a negative result, but also recommends that people who are asymptomatic but believe they have been exposed get three tests instead of two.
The new guide says:
- If an initial or repeat test is positive, follow CDC guidance on isolation and seek medical attention.
- If your first test is negative and you have symptoms, get tested again 48 hours later. You can choose to get tested again 48 hours after the second test, and you may also consider getting a molecular laboratory (PCR) test and seeking medical attention.
- If your first test is negative, you have no symptoms, but you believe you have been exposed, get tested again 48 hours later, then again 48 hours after the second negative test, for a total of at least three tests. After three negative tests, if you are concerned, the FDA suggests getting tested again at home, taking a PCR test, or seeking medical advice.
Current CDC guidelines recommend testing at home immediately if you have symptoms. If you have been exposed to COVID-19, they recommend testing at least 5 days after exposure, and if that test is negative, they suggest testing again 1 or 2 days later.
The FDA's new guidance is based on findings from a new study by researchers at the University of Massachusetts Chan School of Medicine that showed the new timeframes are more likely to detect an infection.
Researchers evaluated 5,609 people enrolled in the national Test Us At Home study from October 2021 to January. Participants used one of three retail testing kits and also collected a sample for a molecular PCR test. They were tested every 48 hours for 15 days.
During the study period, 154 people tested positive for the coronavirus that causes COVID-19, according to PCR samples. After conducting two at-home tests within 48 hours, over 90% of infections were detected in symptomatic individuals who began testing within the first week.
Testing serially three times with a home test at 48-hour intervals detected more than 75% of infections, up from approximately 60% after performing only two tests.
The study is published as a preprint and has not yet been peer-reviewed.