Independent Evaluation of Four SARS-CoV-2 Antigen Rapid Tests Against qRT-PCR in Niger
TL;DR
Only the Panbio nasopharyngeal test met both WHO criteria of sensitivity ≥80% and specificity ≥ 97%.
Abstract
Background: Reliable, decentralised SARS-CoV-2 testing was a major challenge during the COVID-19 pandemic, particularly in low and middle-income countries where molecular capacity was limited. Antigen rapid diagnostic tests (Ag-RDTs) offered a practical alternative, but their field performance varied and locally generated data were needed to guide policy. Objectives: We indepently evaluated four commercial Ag-RDTs, including an African manufactured test, under routine conditions in Niger to inform the national COVID-19 testing algorithm. Methods: Between July 2021 and September 2023, four independent prospective evaluations were conducted among symptomatic patients (symptom onset ≤7 days) at two health facilities in Niamey. Each test namely STANDARD Q nasopharyngeal, Panbio nasopharyngeal and nasal and SAYTU nasal was assessed against qRT-PCR. Sensitivity and specificity were estimated with 95% confidence intervals. Results: Across the four evaluations, 956 patients were tested and 422 (44.1%) were qRT-PCR positive. Sensitivity was 85.7% for the Panbio nasopharyngeal test, 80.1% for the SAYTU nasal test, 76.3% for the Panbio nasal test and 75.0% for the STANDARD Q nasopharyngeal test; specificity exceeded 95% for all four. Sensitivity was highest in high-viral-load specimens. Conclusion: Only the Panbio nasopharyngeal test met both WHO criteria of sensitivity ≥80% and specificity ≥ 97%. However, the other three tests, including the Africa-manufactured SAYTU assay, may support screening where molecular capacity is limited, provided that negative results in symptomatic patients are confirmed by qRT-PCR.