SARS-CoV-2 Rapid Antigen Test Performance in Children
Rapid antigen tests for SARS-CoV-2 first became available in May 2020, when the FDA issued emergency use authorization for Quidel Corporation's Sofia 2 SARS Antigen FIA. Since then, dozens of such tests have become available.
Although rapid antigen tests have been reported to be less sensitive in detecting SARS-CoV-2 infection in adults than their manufacturers claimed, their performance in children has remained unknown until recently.
A research team at the University of Manchester in the United Kingdom undertook the first meta-analysis to evaluate the performance of SARS-CoV-2 rapid antigen tests for children. The researchers reviewed 17 studies involving 6,355 children that compared rapid antigen test results with the gold standard reverse transcription polymerase chain reaction (RT-PCR). The studies included eight different rapid antigen tests from six different companies.
Overall, the pooled diagnostic sensitivity and specificity of the rapid tests were 64.2% and 99.1%, respectively. In children with symptoms, diagnostic sensitivity and specificity were 71.8% and 98.7%, respectively, and in children without symptoms, sensitivity and specificity were 56.2% and 98.6%, respectively.
WHO and FDA standards state that rapid antigen tests should have a minimum sensitivity of 80% and a minimum specificity of 97%. This meta-analysis indicated that rapid antigen tests met the WHO and FDA standard for specificity but failed to meet the standard for sensitivity when testing either symptomatic or asymptomatic children.
Sensitivity is the probability that a test correctly identifies all positive cases. The higher the sensitivity, the lower the likelihood of false-negative results. Specificity is the probability that a test will be negative in uninfected individuals. The higher the specificity, the lower the risk of false-positive results.
This study demonstrated that positive rapid antigen tests in children were reliable because specificity ws high and the chance of a false positive test result was very low. On the other hand, interpretation of negative rapid antigen test results in children was very unreliable because sensitivity was very low and the chance of a false negative test result was high. Parents of symptomatic children who received a negative result from a rapid antigen test should probably seek confirmation with a PCR test.
Reference
Fujita-Rohwerder et al. Diagnostic accuracy of rapid point-of-care tests for diagnosis of current SARS-CoV-2 infections in children: a systematic review and meta-analysis. Brit Med J. 2022, Epub ahead of print, http://dx.doi.org/10.1136/bmjebm-2021-111828
