This study showed that rRT-PCR may produce initial false-negative results. Combining this with other testing modalities may improve sensitivity.
Our data on testing are still relatively new. This was a retrospective cohort study of 36 patients suspected of infections with COVID-19 who were examined by both CT and rRT-PCR at initial presentation. The sensitivities of both tests were compared.
Thirty-five patients had abnormal CT findings at presentation; only one patient had a normal CT. Using rRT-PCR, 30 patients were tested positive, with 6 negative. Three of the six became positive after a second rRT-PCR assay 2-3 days later, and the other 3 became positive after a third rRT-PCR tests 5-8 days later.
At presentation, CT sensitivity was therefore 97%, compared to a sensitivity of initial rRT-PCR of only 83%.