The following is a summary of “Comparative diagnostic utility of SARS-CoV-2 rapid antigen and molecular testing in a community setting,” published in the March 2024 issue of Infectious Diseases by Kim et al.

SARS-CoV-2 rapid antigen tests (Ag-RDTs) are widely used, but their performance over time in communities is unknown.

Researchers compared the sensitivity and specificity of Ag-RDT and rRT-PCR testing within 24 hours.

They conducted a study at a major public university in Seattle, WA, utilizing remote enrollment, online surveys, and self-collected nasal swab specimens to evaluate Ag-RDT performance against real-time reverse transcription polymerase chain reaction (rRT-PCR) during the SARS-CoV-2 Omicron period. The sensitivity and specificity was assessed within 1 day of rRT-PCR, considering symptom status throughout the illness episode and Orf1b cycle threshold (Ct).

The results showed 5,757 individuals undergoing 17,572 Ag-RDT tests and 12,674 rRT-PCR tests between February and December 2022. Of these, 995 (7.9%) were rRT-PCR-positive. Overall sensitivity was 53.0% (95% CI: 49.6-56.4%), and specificity was 98.8% (98.5-99.0%). Sensitivity was higher at 1 day after rRT-PCR (69.0%), 4-7 days post-symptom onset (70.1%), and Orf1b Ct ≤20 (82.7%). Serial Ag-RDT testing increased sensitivity: ≥2 tests (68.5%), ≥4 tests (75.8%) after initial negative results.

Investigators concluded that Ag-RDT performance varied by clinical factors and testing timing. Our results endorse serial testing post-initial negative results, particularly for recent symptoms or high-risk individuals.

Source: academic.oup.com/jid/advance-article-abstract/doi/10.1093/infdis