Rapid antigen tests for COVID-19 are useful, but not all are created equal

Overall, this review suggests that in symptomatic individuals in the first few days of symptoms, the most accurate rapid antigen tests are a useful alternative to laboratory‐based RT‐PCR, where immediate results are required for timely patient management.

However, rapid antigen tests are only sufficiently sensitive in the first week from onset of symptoms. At 80% sensitivity compared with RT‐PCR, the probability that infected individuals are missed is 20% higher than for RT‐PCR.

Thus, the possibility of false negative results should be considered in those with a high clinical suspicion of COVID‐19, particularly if tested several days after onset of symptoms when viral load levels may have fallen.

Rapid antigen tests may be used simultaneously in combination with RT‐PCR for symptomatic people, particularly where RT‐PCR turn‐around times are slow, to exploit the benefits of earlier results and consequent isolation and contact tracing.

For rapid antigen test evaluations in symptomatic participants, this review observed considerable heterogeneity in sensitivities (and, to a lesser extent, the specificities). WHO has set a minimum “acceptable” sensitivity requirement of 80%; and acceptable and ideal (or “desirable”) specificity requirements of 97% and 99%, respectively.

For the 2 tests available in New Zealand from the list of tests studied (SD Biosensor, Abbott Panbio), only SD Biosensor met the WHO acceptable criterion of more than 80% sensitivity based on pooled results of several studies, while Abbott Panbio met the sensitivity criterion in some individual studies but not overall. Both SD Biosensor and Abbott Panbio met the desirable criterion of more than 99% specificity.