RESUMO
The Omicron variant of concern has a high level of mutations in different genes that has raised awareness about the performance of immunological products such as vaccines and antigen detection kits. In this systematic review and meta-analysis, we investigated whether Omicron had a significant influence on rapid antigen test (RAT) performance in comparison to PCR. We registered this systematic review and meta-analysis in PROSPERO with the registration number CRD42022355510. We searched PubMed, Scopus, Embase, and Web of Science databases systematically to 1 August 2022. After article screening, we assessed the quality of the included studies based on the JBI checklist. Following data extraction, we performed a meta-analysis using R software. We included 18 qualified articles presenting sufficient data about RATs performance in comparison to RT-PCR in Omicron infections. The pooled specificity and sensitivity of RATs were 1.000 (0.997-1.000) and 0.671 (0.595-0.721), respectively. The FDA-approved kits showed a better performance than WHO-approved ones with a sensitivity of 0.728 (0.620-0.815). The use of RATs with nasal swabs showed a higher sensitivity compared with nasopharyngeal swabs. The sensitivity for samples with a CT-value >25 was 0.108 (0.048-0.227). Rapid antigen tests show impaired performance for COVID-19 diagnosis when the Omicron variant is circulating, particularly in samples with low viral loads.