Background Viral and immune kinetics in mild to moderate COVID-19 are understudied because of challenges inherent in longitudinal sampling of people who are infectious to others, feeling ill, yet are not hospitalized. In particular, sustained molecular detection of SARS-CoV-2 RNA in the upper respiratory tract (URT) in mild to moderate COVID-19 is common and confounds surveillance efforts in the community. We sought to identify host and immune determinants of prolonged SARS-CoV-2 RNA detection via longitudinal viral RNA, virus culture, and plasma and oral fluid antibody sampling in a prospective observational cohort study of adult outpatients with COVID-19. Methods and Findings Samples from 95 non-hospitalized participants [≥] 30 years old with recent COVID-19 diagnosis and known symptom onset date were analyzed. Participants self-collected mid-turbinate nasal, oropharyngeal (OP), and gingival crevicular fluid (oral fluid) samples at home and in a research clinic a median of 6 times over 1-3 months. SARS-CoV-2 RT-PCR performed on 507 URT samples revealed a median time to viral RNA clearance of the URT of 33.5 days. Sixteen nasal-OP samples collected 2-11 days post-symptom onset were virus culture positive out of 183 RT-PCR positive samples tested. All participants but one with positive virus culture were negative for concomitant oral fluid anti-SARS-CoV-2 spike-receptor binding domain (S-RBD) antibodies. The kinetics of oral fluid anti-SARS-Cov-2 antibodies were measured using a multiplex immunoassay. The mean time to first detection of oral fluid anti-SARS-CoV-2 antibodies was 8-13 days post-symptom onset. Associations of symptoms, host demographics, comorbidities, and immune kinetics with time to SARS-CoV-2 RNA clearance were estimated using Cox proportional hazards models. A longer time to first detection of oral fluid anti-SARS-CoV-2 S antibodies was independently associated with a longer time to SARS-CoV-2 viral RNA clearance (aHR 0.96, 95% CI 0.92-0.99, p=0.020). BMI [≥] 25kg/m2 was also independently associated with a longer time to viral RNA clearance (aHR 0.37, 95% CI 0.18-0.78, p=0.009). Fever reported as one of first three COVID-19 symptoms was associated with shorter time to viral RNA clearance (aHR 2.06, 95% CI 1.02-4.18, p=0.044). Plasma titers of neutralizing antibodies, SARS-CoV-2 spike (S) antibodies, and S-receptor binding domain (S-RBD) antibodies were obtained at 1-4 months post-symptom onset. BMI was positively correlated with post-acute plasma SARS-CoV-2-specific neutralizing antibody titer and anti-S-RBD antibody titer. Conclusions In an intensively sampled cohort of 95 adult outpatients with COVID-19, we demonstrate that longer time to first detection of oral fluid SARS-CoV-2-specific antibodies, elevated BMI, and absence of early fever are independently associated with longer time to viral RNA clearance. This work provides insights into the host and immune factors most important for viral clearance in mild to moderate COVID-19.
Delayed rise of oral fluid antibodies, elevated BMI, and absence of early fever correlate with longer time to SARS-CoV-2 RNA clearance in an longitudinally sampled cohort of COVID-19 outpatients