Viral load and infectivity of SARS-CoV-2 in paired respiratory and oral specimens from symptomatic, asymptomatic or post-symptomatic individuals

In the present study, we assessed the diagnostic sensitivity and determined the viral load and infectivity of SARS-CoV-2 in paired respiratory (nasopharyngeal and anterior nares) and oral samples (saliva and sublingual swab). Samples were collected from 77 individuals of which 75 were diagnosed with COVID-19 and classified as symptomatic (n=29), asymptomatic (n=31), or post-symptomatic (n=15). Specimens were collected at one time point from each individual, between day 1 to 23 after the initial COVID-19 diagnosis, and included self-collected saliva (S), or sublingual (SL) swab, and bilateral anterior nares (AN) swab, followed by healthcare provider collected nasopharyngeal (NP) swab. Sixty-three specimen sets were tested using five assay/platforms. The diagnostic sensitivity of each assay/platform and specimen type was determined. Of the 63 specimen sets, SARS-CoV-2 was detected in 62 NP specimens, 52 AN specimens, 59 saliva specimens, and 31 SL specimens by at least one platform. Infectious SARS-CoV-2 was isolated from 21 NP, 13 AN, 12 saliva, and one SL specimen out of 50 specimen sets. SARS-CoV-2 isolation was most successful up to 5 days after initial COVID-19 diagnosis using NP specimens from symptomatic patients (16 of 24 positives, 66.67%), followed by specimens from asymptomatic patients (5 of 17 positives, 29.41%), while it was not very successful with specimens from post-symptomatic patients. Benefits of self-collected saliva and AN specimens balance the loss of sensitivity relative to NP specimens. Therefore, saliva and AN specimens are acceptable alternatives for symptomatic SARS-CoV-2 diagnostic testing or surveillance with increased sampling frequency of asymptomatic individuals.