Field evaluation of a rapid antigen test (Panbioâ„¢ COVID-19 Ag Rapid Test Device) for COVID-19 diagnosis in primary healthcare centers

Albert, Eliseo; Torres, Ignacio; Bueno, Felipe; Huntley, Dixie; Molla, Estefanía; Fernández-Fuentes, Miguel Ángel; Martínez, Mireia; Poujois, Sandrine; Forqué, Lorena; Valdivia, Arantxa; Solano de la Asunción, Carlos; Ferrer, Josep; Colomina, Javier; Navarro, David

OBJECTIVES: To our knowledge no previous study has assessed the performance of a rapid antigen diagnostic immunoassay (RAD) conducted at the point of care (POC). We evaluated the Panbio™ COVID-19 Ag Rapid Test Device for COVID-19 diagnosis in symptomatic patients (n=412) attended in primary healthcare centers. METHODS: RAD was performed immediately after sampling following the manufacturer’s instructions (reading at 15 min.). RT-PCRs were carried out within 24 h. of specimen collection. Samples displaying discordant results were processed for culture in Vero E6 cells. Presence of SARS-CoV-2 in cell cultures was confirmed by RT-PCR. RESULTS: Out of 412 patients, 43 (10.4%) tested positive by RT-PCR and RAD and 358 (86.9%) negative by both methods, showing discordant results (RT-PCR+/RAD-) in 11 patients (2.7%). Overall specificity and sensitivity of rapid antigen detection (RAD) was 100% (95% CI, 98.7-100%), and 79.6% (95% CI, 67.-88.8%), respectively, taking RT-PCR as the reference. Overall RAD negative predictive value for an estimated prevalence of 5% and 10% was 99% (95% CI, 97.4-99.6%) and 97.9% (95% CI, 95.9-98.9), respectively. SARS-CoV-2 could not be cultured from specimens yielding RT-PCR+/RAD-results (n=11). CONCLUSION: The Panbio™ COVID-19 Ag Rapid Test Device performed well as a POCT for early diagnosis of COVID-19 in primary healthcare centers. More crucially, the data suggested that patients with RT-PCR-proven COVID-19 testing negative by RAD are unlikely to be infectious.