Evaluating real-world data in COVID-19 antigen and PCR testing

Objective: COVID-19 testing is an important pillar in fighting the SARSCoV-2 pandemic. Even though billions of tests have been conducted, little is known on performance of testing sites. This is a retrospective observational study with real world data from a pharmacist-led COVID-19 testing center in Germany during the Omicron subvariant BA.4 and BA.5 wave in June 2022. Materials: The rapid antigen tests employed were purchased from Anbio Biotechnology (Xiamen, China). The RT-PCR was performed on Egens YS-qPCR-1 real-time system with Kewei multiple real-time PCR kits for detection of SARS-CoV-2 (Beijing Kewei Clinical Diagnostic Reagent Inc., Beijing, China). Methods: The study followed the STARD 2015 guideline. In this retrospective cohort study, the performance of testing sites was compared. Results: During the study period, 7,112 patients were tested by rapid antigen tests and 1,025 RT-PCR tests conducted. Included were 233 patients who were referred by other testing sites for confirmation of positive results. A positive predictive value of 99.6% was calculated for the antigen tests in the pharmacist-led testing center. Referred positive patients from nonmedical sites were antigen and RT-PCR negative in 16 cases, which led to a positive predictive value of 88.8%. Difference between site performance was statistically significant (p < 0.05). Conclusion: Results indicate that nucleic acid amplification confirmation is crucial in the context of the current testing strategy in Germany. Higher standards in antigen-testing, however, can make nucleic acid amplification in active COVID-19 infections unnecessary and testing cost efficient. This study provides the first data in the world on COVID-19 testing performance, and how it can be optimized.