RESUMO
BackgroundPre-/asymptomatic close contacts of SARS-CoV-2 infected individuals were tested at day 5 after contact by real-time reverse transcriptase polymerase chain reaction (RT-PCR). Diagnostic accuracy of antigen-detecting rapid diagnostic tests (Ag-RDT) in pre-/asymptomatic close contacts was up till now unknown. MethodsWe performed a prospective cross-sectional diagnostic test accuracy study. Close contacts (e.g. selected via the test-and-trace program or contact tracing app) aged [≥]16 years and asymptomatic when requesting a test, were included consecutively and tested at day 5 at four Dutch public health service test sites. We evaluated two Ag-RDTs (BD Veritor System Ag-RDT (BD), and Roche/SD Biosensor Ag-RDT (SD-B)) with RT-PCR as the reference standard. Virus culture was performed in RT-PCR positive individuals to determine the viral load cut-off above which 95% was culture positive, as a proxy of infectiousness. ResultsOf 2,678 BD-tested individuals, 233 (8.7%) were RT-PCR positive and BD detected 149 (sensitivity 63.9%; 95% confidence interval 57.4%-70.1%). Out of 1,596 SD-B-tested individuals, 132 (8.3%) were RT-PCR positive and SD-B detected 83 (sensitivity 62.9%; 54.0%-71.1%). When applying an infectiousness viral load cut-off [≥] 5.2 log10 gene copies/mL, the sensitivity was 90.1% (84.2%-94.4%) for BD, 86.8% (78.1% to 93.0%) for SD-B overall, and 88.1% (80.5%-93.5%) for BD, 85.1% (74.3%-92.6%) for SD-B for those still asymptomatic at the actual time of sampling. Specificity was >99% for both Ag-RDTs in all analyses. ConclusionsThe sensitivity for detecting SARS-CoV-2 of both Ag-RDTs in pre-/asymptomatic close contacts is over 60%, increasing to over 85% after applying an infectiousness viral load cut-off. Trial registration numberNot applicable. A study protocol is available upon request.
RESUMO
ObjectivesThis study was primarily conducted to evaluate clinical sensitivity and specificity of the SARS-CoV-2 rapid antigen test BD Veritor System for Rapid Detection of SARS-CoV-2 (VRD) compared to real time reverse transcriptase polymerase chain reaction (qRT-PCR). Furthermore, the VRD sensitivity for different Ct-value groups (Ct <20; Ct 20-25, Ct 25-30 and Ct [≥]30) and different intervals since symptom onset (< 7 days; [≥] 7 days) were examined. DesignProspective performance evaluation study. SettingMunicipal Health Service (GGD) COVID-19 test centres in West-Brabant, the Netherlands ParticipantsIn order to evaluate clinical specificity, 352 symptomatic adults ([≥]18 years) who presented at a participating GGD test centre for a COVID-19 test between September 28 and October 7 2020 were included. In order to evaluate clinical sensitivity, 123 symptomatic adults ([≥]18 years) who were tested positive with qRT-PCR in a participating GGD test centre between September 26 and October 6 were included. ResultsAn overall clinical specificity of 100% (95%CI: 98.9%-100%) and sensitivity of 80.7% (95% CI: 73,2%-86,9%) was found for the VRD compared to qRT-PCR. Sensitivity was the highest for low Ct-value categories and for specimen obtained within the first days after disease onset. For specimen obtained within 7 days after onset of symptoms, the overall sensitivity was 91.0% (95% CI: 82,4%-96,3%) and 98,6% (95% CI: 92,3%-100%) for samples with qRT-PCR Ct-value beneath 30. ConclusionThe VRD is a promising diagnostic test for COVID-19 community screening for symptomatic individuals within 7 days after symptom onset in function of disease control. The clinical sensitivity was highest when viral load was high, which correlated with the duration of symptoms. Further research on practical applicability and the optimal position of the test within the current testing landscape is needed.
