Assessment of performance and implementation characteristics of rapid point of care SARS-CoV-2 antigen testing

Abstract

Background: The COVID-19 pandemic has resulted in a need for rapid identification of infectious cases. Testing barriers have prohibited adequate screening for SARS-CoV-2, resulting in significant delays in commencement of treatment and outbreak control measures. This study aimed to generate evidence on the performance and implementation characteristics of the BD Veritor™ Plus System rapid antigen test as compared to reverse transcription polymerase chain reaction (RT-PCR) for diagnosis of SARS-CoV-2 in Kenya. Methods: This was a field test performance evaluation in adults undergoing testing for SARS-CoV-2. Recruited participants were classified as SARS-CoV-2-positive based on RT-PCR carried out on nasopharyngeal swabs. Antigen tests were performed with simultaneous RT-PCR on 272 participants, allowing estimation of sensitivity, specificity, positive and negative predictive values for the rapid antigen test. Implementation characteristics were assessed. Results: We enrolled 97 PCR negative symptomatic and 128 PCR negative asymptomatic, and 28 PCR positive symptomatic and 19 PCR positive asymptomatic participants. Compared to RT-PCR, the sensitivity of the rapid antigen test was 94% (95% confidence interval [CI] 86.6 to 100.0) while the specificity was 98% (95% CI 96 to 100). There was no association between sensitivity and symptom status, or between the cycle threshold value and sensitivity of the BD Veritor. The rapid test had a quick turnaround time, required minimal resources, and laboratory personnel conducting testing found it easier to use than RT-PCR. The relatively high sensitivity of BD Veritor may be partially attributed to shortages of RT-PCR testing materials, resulting in specimen analysis delays and potential degradation of viral genetic material. Therefore, in resource-constrained settings, rapid antigen tests may perform better than the reference RT-PCR, resulting in prompt institution of isolation and treatment measures. Conclusion: The BD Veritor rapid antigen test’s high sensitivity should be interpreted with consideration to the challenges occasioned by RT-PCR testing in resource-constrained settings.

Systematic Approach to Address Early Pandemic's Diagnostic Unmet Needs

“…However, the supply chain of rapid tests was severely limited until the end of 2020. We were subsequently able to access some platforms to evaluate in Massachusetts (Suliman et al, 2021), and in collaboration with global partners who relied more on rapid tests to expand decentralized testing in resource-constrained settings (Kawser et al, 2022;Muthamia et al, 2022). These rapid tests necessitate different parameters in our evaluation rubric since they are known to have lower sensitivities than molecular tests, but can be powerful tools for screening highly infectious individuals with high SARS-CoV-2 viral loads (Guglielmi, 2020;Ricco et al, 2022).…”