Comparing SARS-CoV-2 home testing with RT-PCR and viral culture. Individuals with symptoms of COVID-19 who initially test negative on home antigen tests should retest one to two days after symptom onset, according to research reported in the July JAMA Internal Medicine. Researchers compared same-day reverse transcription-polymerase chain reaction (RT-PCR) results with home antigen tests in 225 people with RT-PCR-confirmed SARS-CoV-2 infection over 15 days. They found that the sensitivity of home antigen tests increased over the early course of the illness, peaking at 77% on day 4. Six days after symptom onset, the positivity rates remained high-86% for RT-PCR and 61% for home antigen tests-but by day 11, while the positivity rate for RT-PCR was still at 86% (this test is known to remain positive long after recovery), it was only 16% on home antigen tests. The authors note that these findings support current Centers for Disease Control and Prevention recommendations for antigen testing to determine infectivity after five days and continued isolation up to 10 days for those with positive results.