Comparative analyses of all FDA EUA-approved rapid antigen tests and RT-PCR for COVID-19 quarantine and surveillance-based isolation

WELLS, C.; Pandey, A.; Moghadas, S.; Singer, B. H.; Krieger, G.; Herron, R. J. L.; Turner, D. E.; Abshire, J. P.; Phillips, K. M.; Donoghue, A. M.; Galvani, A. P.; Townsend, J. P.

Rapid antigen (RA) tests are being increasingly employed for detection of COVID-19 infections in implementations of quarantine and surveillance. We conducted a comparative analysis of quarantine durations, testing frequencies, and false-positive rates for all of the 18 RA tests for which emergency use authorization (EUA) has been given by the FDA and a nasopharyngeal RT-PCR test. For each test, we employed a mathematical model of imminent infections to calculate the effective reproductive number in the context of the test used for quarantine or serial testing strategy. We informed the model with data on test specificity and temporal diagnostic sensitivity, convolved with a data-driven profile of COVID-19 infectiousness across the disease time course. Our results demonstrate that the relative effectiveness of RA and RT-PCR tests in reducing post-quarantine transmission depends on the duration of quarantine and the turnaround time of testing results. When quarantines are shorter than five days, our results suggest that an RA test on entry to and on exit from quarantine would reduce onward transmission more than a single RT-PCR test conducted upon exit. Conducting surveillance via serial RT-PCR testing with a 24-h turnaround time, the testing frequency paired with isolation of positives that is required to suppress the effective reproduction number (RE) below one was found to require a minimum frequency of every six days. RA tests reduce RE below one when conducted at a minimum frequency that ranges from every six days to every eight days--depending on the type of RA test--with a median of seven days. Our analysis also highlights that the risk of onward transmission during serial testing increases with the delay in obtaining the results. False-positives were found to be more frequent with RA tests, an issue that could be mitigated with clinical and RT-PCR follow-up. Accounting for the specific diagnostic traits of RA tests, they are an important component of the tool set for policy decision-making, and can serve as a viable alternative to RT-PCR in efforts to control the spread of disease.