Combining Rapid Antigen Testing and Syndromic Surveillance Improves Sensitivity and Specificity of COVID-19 Detection: A Community-Based Prospective Diagnostic Study

Background: Diagnostics for COVID-19 detection are limited in many settings. Syndromic surveillance is often the only means to identify cases, despite lack of specificity and asymptomatic cases. Rapid antigen testing is inexpensive and easy-to-deploy but concerns remain about sensitivity. We examine how combining these approaches can improve surveillance for guiding interventions. Methods: Community-based volunteers were trained to syndromically assess potential COVID-19 cases in low-income communities in Dhaka, Bangladesh. Rapid antigen tests and PCR validation was performed on 1172 syndromically-identified individuals at their households. Statistical models were fit to predict PCR status using rapid-antigen-test results, syndromic data, and their combination. Model predictive and classification performance was examined under contrasting epidemiological scenarios to evaluate their potential for improving diagnoses. Findings: Models combining…