Study suggests repeat home antigen testing for Covid after first negative result

STAT:

Home antigen tests for Covid-19 win for convenience but may not measure up to the accuracy of PCR testing. A new study published in JAMA Internal Medicine explores a different question: how well antigen testing performs over the course of illness.

Researchers followed 225 people who had Covid infections confirmed by PCR testing, as well as their household members. After daily testing for 15 days, home antigen test sensitivity peaked three days after illness onset, at 80% for symptomatic cases and 50% for asymptomatic cases.

The researchers warn that antigen test positivity was lower before and on the first day people felt symptoms. “Individuals with a high pretest probability of SARS-CoV-2 infection and initial negative home antigen test result should consider repeating an antigen test in 1 to 2 days or obtaining a confirmatory RT-PCR,” they write.