Two RATs instead of one can sniff out false positives

Embargoed until: Publicly released: 2022-03-19 02:00

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Taking a second rapid antigen test immediately after a positive result could reduce the amount of false COVID-19 positives, according to international researchers. The team looked at a US company regularly RAT testing its asymptomatic workers during a time of low COVID-19 cases in the community, and found when cross-checking positive RATs with PCR tests that about 62 per cent of the positive results were false positives. When giving a second RAT to those who tested positive the first time, the researchers say 92 per cent of people who received two positive RATs went on to test positive with a PCR. For those who received a negative result on their second RAT, they say 95 per cent tested negative on a PCR. The researchers say this shows giving positive employees a second RAT could prove useful, but they note the high rate of false positives was likely influenced by low cases in the community and therefore a lower likelihood of true positives.