Evaluation of the performance of a rapid antigen test (Roche) for COVID‐19 diagnosis in an emergency setting in Sweden

During the ongoing COVID‐19 pandemic, rapid and reliable detection of SARS‐CoV‐2 is important to enable proper care of patients and to prevent further transmission. The aim of this study was to evaluate the performance of the Roche SARS‐CoV‐2 Rapid Antigen Test (Ag‐RDT) in an emergency care setting during a high pandemic period. The analytical performance of the Ag‐RDT was compared to real‐time reverse transcriptase polymerase chain reaction (rRT‐PCR). A total of 132 patient samples, previously analyzed with rRT‐PCR, were reanalyzed with the Ag‐RDT. Tenfold serial dilutions of five different patient strains containing the pangolin variants BA.1, BA.2, B.1.1.7, B.1.160, and B.1.177 were analyzed in parallel with the Ag‐RDT and rRT‐PCR. A clinical evaluation was performed in which 1911 consecutive patients admitted to the emergency wards in Region Gävleborg, Sweden, were included. Paired samples were collected and analyzed with the Ag‐RDT on‐site and with rRT‐PCR at the microbiology laboratory. The overall sensitivity and specificity of the Ag‐RDT in the clinical evaluation were 71.3% and 99.7%, respectively. When samples with cycle threshold (Ct) values above 30 were excluded, the sensitivity was 86.5%. Eleven of the admitted patients who were positive for both the Ag‐RDT and rRT‐PCR (Ct‐range 16.9–30.4) showed no symptoms of COVID‐19. Using the Ag‐RDT shortened the detection time by an average of 11 h. The Ag‐RDT is a useful tool for preliminary screening of SARS‐CoV‐2 because it enables rapid detection in infectious individuals and therefore, can counteract unnecessary spread of infection at an early stage.