Prolonged persistence of SARS-CoV-2 in the upper respiratory tract of asymptomatic infected individuals

Saurabh, Suman; Kumar, Ritesh; Gupta, Manoj Kumar; Bhardwaj, Pankaj; Nag, Vijaya Lakshmi; Garg, Mahendra Kumar; Misra, Sanjeev

BACKGROUND: Duration of persistence of SARS-CoV-2 in the upper respiratory tract of infected individuals has important clinical and epidemiological implications. AIM: We aimed to establish the duration and risk factors for persistence of SARS-CoV-2 in the upper respiratory tract of asymptomatic infected individuals. METHODS: Data of repeat rRT-PCR test done for SARS-CoV-2 infected individuals at our institute at Jodhpur, India was analysed from 19 March- 21 May 2020. Duration of virus persistence was estimated with parametric regression models based on Weibull, Log-normal, Log-logistic, Gamma and Generalized Gamma distributions. Factors associated with prolonged viral persistence were analysed with the best fitting model. RESULTS: 51 SARS-CoV-2 infected individuals with repeat rRT-PCR test were identified with 44 asymptomatics. The asymptomatic individuals had median virus persistence duration of 8.87 days (95%CI: 7.65 – 10.27) and 95 percentile duration of 20.70 days (95% CI: 16.08 -28.20). The overall median virus persistence including both symptomatic and asymptomatic individuals was found to be 9.18 days (95 CI 8.04 – 10.48). Around one-fourth asymptomatics (10/44) demonstrated SARS-CoV-2 persistence beyond 2 weeks. Age < 60 years and local transmission were found to be significantly associated with longer virus persistence among asymptomatic individuals on univariate regression but not in multivariate analysis. CONCLUSION: Recommended home isolation duration for SARS-CoV-2 infected individuals in India should be extended from 17 days to at least three weeks. Prolonged persistence of SARS-CoV-2 in a proportion of asymptomatic individuals merits attention with regard to ensuring universal infection prevention precautions irrespective of symptomatic status.