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

• Published in: QJM : An International Journal of Medicine Vol. 113; no. 8; pp. 556 - 560
• Main Authors: Saurabh, S, Kumar, R, Gupta, M K, Bhardwaj, P, Nag, V L, Garg, M K, Misra, S
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01-08-2020
• Subjects: Adolescent; Adult; Age Factors; Aged; Asymptomatic Infections; Betacoronavirus - isolation & purification; Clinical Laboratory Techniques - methods; Coronavirus Infections - diagnosis; Coronavirus Infections - transmission; Coronavirus Infections - virology; COVID-19; COVID-19 Testing; Female; Humans; India; Male; Middle Aged; Nasopharynx - virology; Original Papers; Oropharynx - virology; Pandemics; Pneumonia, Viral - diagnosis; Pneumonia, Viral - transmission; Pneumonia, Viral - virology; Reverse Transcriptase Polymerase Chain Reaction - methods; Risk Factors; SARS-CoV-2; Time Factors; Virus Shedding; Young Adult; India
• ISSN: 1460-2725; 1460-2393
• DOI: 10.1093/qjmed/hcaa212

Summary
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 (real-time reverse transcription-polymerase chain reaction) test done for SARS-CoV-2 infected individuals at our institute at Jodhpur, India were analysed from 19 March to 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
Fifty-one 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 3 weeks. Prolonged persistence of SARS-CoV-2 in a considerable proportion of asymptomatic individuals merits attention with regard to ensuring universal infection prevention precautions irrespective of symptomatic status.