The Performance of a Rapid Coronavirus Disease 2019 Antigen Test in Rural Gabon

Access to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing is limited in rural sub-Saharan Africa. We evaluated the performance of the Siemens CLINITEST® rapid coronavirus disease 2019 antigen test under real-life conditions during the pandemic in rural Gabon. From August 2021 to February 2022, 277 participants were tested in Sindara and Lambaréné, Gabon, via outpatient mobile services. Of these participants, 54.6% were female, with a median age of 29 years (interquartile range: 12-55). The test performance was analyzed for the main population and for SARS-CoV-2 infected sub-populations at both study sites (Lambaréné and Sindara). We further evaluated subpopulations with higher viral loads using a cycle threshold (Ct) value restricted to <35, 30, 25, and 20. Overall test sensitivity in the main population was 33.3% (95% CI: 23.6-44.3%), improving to 83.3% (95% CI: 35.9-99.6%) with a Ct value of <20. Specificity across all populations was 100% (190/190; 95% CI: 98.1-100%). The prevalence of polymerase chain reaction-defined SARS-CoV-2 was 31.4%. The positive predictive value was 100% (95% CI: 88.1-100%), and negative predictive value was 76.6% (95% CI: 70.8-81.7%). Sensitivity in Sindara was 71.4% (95% CI: 29-96.3%) and 30% (95% CI: 20.3-41.3%) in Lambaréné. The Siemens CLINITEST® demonstrated high specificity but low sensitivity overall. However, it exceeded the WHO-defined quality criteria of 80% in participants with high viral loads, making it a useful tool in resource-limited settings.