Implications in the quantification of SARS-CoV2 copies in concurrent nasopharyngeal swabs, whole mouth fluid and respiratory droplets.
SARS-CoV-2, nasopharyngeal swab, respiratory droplet, whole mouth fluid, quantitation
Association of SARS-CoV2 burden in the aerodigestive tract with the disease is sparsely understood. We propose to elucidate the implications of SARS-CoV2 copies in concurrent nasopharyngeal swab (NPS), whole mouth fluid (WMF) and respiratory droplet (RD) samples on disease pathogenesis/transmission. SARS-CoV2 copies quantified by RT-PCR in concurrent NPS, WMF and RD samples from 80 suspected COVID-19 patients were analysed with demographics, immune response and disease severity. Among the 55/80 (69%) NPS-positive patients, SARS-CoV2 was detected in 44/55 (80%) WMF (concordance with NPS-84%; p = 0.02) and 17/55(31%) RD samples. SARS-CoV2 copies were similar in NPS (median:8.74 × 10^5) and WMF (median:3.07 × 10^4), but lower in RD (median:3.60 × 10^2). The 25-75% interquartile range of SARS-CoV2 copies in the NPS was significantly higher in patients who shed the virus in WMF (p = 0.0001) and RD (p = 0.01). Multivariate analyses showed that hospitalized patients shed significantly higher virus copies in the WMF (p = 0.01). Hospitalized patients with more severe disease (p = 0.03) and higher IL-6 values (p = 0.001) shed more SARS-CoV2 virus in the RD. WMF may be used reliably as a surrogate for diagnosis. High copy numbers in the NPS probably imply early disease onset, while in the WMF and RD may imply more severe disease and increased inflammation.
Chandra Lavanya, Pasuvaraj Mahanathi, Veeraraghavan Ashwini, Nagalingeswaran Kumarasamy, Gunaseelan Rajan, Kannan Ranganathan, Stephen J Challacombe, Priya Kannian, Bagavad Gita Jayaraman, Swarna Alamelu, Jennifer Webster-Cyriaque, Newell W Johnson