Diagnostic accuracy of a rapid diagnostic test for the early detection of COVID-19.

OBJECTIVES: This study was undertaken to evaluate the diagnostic performance of the BinaxNOW COVID-19 Ag Card rapid antigen assay (Abbott; Chicago, IL, USA) in the detection of COVID-19 infection compared to the reference standard of PCR testing. METHODS: We evaluated the BinaxNOW COVID-19 Ag Card rapid antigen assay relative to a standard reference PCR test. We tested 3810 nasal swabs from symptomatic and asymptomatic adults undergoing surveillance COVID-19 testing at Howard University using one swab for each nostril. One swab was tested using the rapid antigen assay and the other using the PCR test. RESULTS: The sensitivity of the BinaxNOW COVID-19 Ag Card rapid antigen assay was 91.84% (95% confidence interval (CI): 80.40-97.73%) and the specificity was 99.95% (95% CI: 99.81-99.99%). The range of Ct values for the N gene was 10.74-34.90 (M = 26.88, SD=4.86). Fourteen (28.6%) samples had an N gene Ct value > 30. The average N gene Ct value for rapid test negative (i.e. false negative) samples was 31.92. CONCLUSIONS: The sensitivity of the test in our symptomatic and asymptomatic cohort was lower than the manufacturer's reported sensitivity in a symptomatic cohort (97.1%). Despite their relatively lower sensitivity (especially in asymptomatic individuals), rapid tests have undeniable benefits (i.e., ease of use and rapid results) that make them a helpful tool in the control of the SARS-CoV-2 pandemic. Given the diagnostic accuracy of these tests as evidenced by this study, rapid tests can be thoughtfully employed in situations where swift results are critical.

Neighborhood stress and autonomic nervous system activity during sleep.

Study Objectives: Stressful neighborhood environments are known to adversely affect health and contribute to health disparities but underlying mechanisms are not well understood. Healthy sleep can provide a respite from sustained sympathetic nervous system (SNS) activity. Our objective was to evaluate relationships between neighborhood stress and nocturnal and daytime SNS and parasympathetic nervous system (PNS) activity. Methods: Eighty-five urban-residing African Americans (56.5% female; mean age of 23.0) participated. Evaluation included surveys of neighborhood stress and sleep-related vigilance, and continuous electrocardiogram (ECG) and actigraphic recording in participants' homes from which heart rate variability (HRV) analysis for low frequency/high frequency (LF/HF) ratio and normalized high frequency (nHF), as indicators of SNS and PNS activity, respectively, and total sleep time (TST), and wake after sleep onset were derived. Results: All significant relationships with HRV measures were from the sleep period. Neighborhood disorder correlated negatively with nHF (r = -.24, p = .035). There were also significant correlations of HRV indices with sleep duration and sleep fears. Among females, LF/HF correlated with exposure to violence, r = .39, p = .008, and nHF with census tract rates for violent crime (r = -.35, p = .035). In a stepwise regression, TST accounted for the variance contributed by violent crime to nHF in the female participants. Conclusions: Further investigation of relationships between neighborhood environments and SNS/PNS balance during sleep and their consequences, and strategies for mitigating such effects would have implications for health disparities.