Application of a SARS-CoV-2 Antigen Rapid Immunoassay Based on Active Microfluidic Technology in a Setting of Children and Young Adults.

To carry out effective and quick identification of SARS-CoV-2 from nasopharyngeal swabs and contain outbreaks, reliable and rapid tools are needed. Herein, we compared a rapid antigen test based on active microfluidic technology to an RT-qPCR assay in pediatric and young adult patients admitted to the Pediatric Emergency Unit of a Children's Hospital. Nasopharyngeal swabs collected from patients with suspected COVID-19 disease and from those without COVID-19 related symptoms, but requiring hospitalization, were performed with both antigen test and RT-qPCR assays. We included 375 patients with a median age of 5 years in the study, with an estimated overall prevalence of 7.2%. Overall, we observed a specificity of 97.4% (95% CI: 94.9-98.7) and a sensitivity of 66.6% (95% CI: 46.0-82.7) with a positive likelihood ratio (LR+) of 25.8 (95% CI: 12.8-51.8). In the subgroup of symptomatic patients, the specificity and the sensitivity were 95.2% (95% CI: 89.4-98.0) and 80.0% (95% CI: 44.2-96.5) respectively; LR+ was 16.6 (95% CI: 7.19-38.6). In the asymptomatic subset, the performance showed a specificity of 98.7% (95% CI: 95.8-99.7), a sensitivity of 58.8% (95% CI: 33.5-80.6), and an LR+ of 43.7 (95% CI: 13.3-144.0). Compared to RT-qPCR, the new microfluidic-based antigen test showed higher specificity (>95%) in the pediatric population, thus representing a suitable point-of-care testing (POCT) in a clinical setting with low prevalence of COVID-19.