Editor's note: This story will be updated.

Aug. 11, 2022 – It 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 repeat testing after a negative result, but is also recommending that people who have no symptoms but think they have been exposed take three tests instead of two.

Current guidelines from the CDC recommend testing at home right away if you get symptoms. If you have been exposed to COVID-19, it recommends testing at least 5 days after exposure – and if that test is negative, it says to consider testing again 1-2 days later.

The new guidance from the FDA is based on findings from a new study by University of Massachusetts Chan Medical School researchers showed the new timelines are more likely to detect an infection.

Researchers evaluated 5,609 people who are enrolled in the national Test Us At Home study, from October 2021 to January. The participants used one of three retail test kits and also collected a sample for a molecular PCR test. They tested every 48 hours for 15 days.

During the study period, 154 people tested positive for the coronavirus that causes COVID-19, based on the PCR samples. After testing twice at home over 48 hours, more than 90% of infections were detected in symptomatic people who began testing within the first week.

Serial testing three times with an at-home test at 48-hour intervals detected more than 75% of infections, an increase from about 60% after testing just twice.

The study is published as a preprint and is not yet peer-reviewed.

MedRxiv: “Performance of Screening for SARS-CoV-2 using Rapid Antigen Tests to Detect Incidence of Symptomatic and Asymptomatic SARS-CoV-2 Infection: findings from the Test Us at Home prospective cohort study.”

FDA Safety Communication: “At-Home COVID-19 Antigen Tests – Take Steps to Reduce Your Risk of False Negative.”

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