Duration of viable SARS-CoV-2 shedding from respiratory tract in different human hosts and its impact on isolation discontinuation polices revision; a narrative review

Abstract

Background: The duration of viable viral shedding is important to be defined in regards of viral transmission in SARS-CoV-2 infection with the backdrop of the current worldwide effort for revising isolation polices and establishing the duration of infectiousness.

Methods: In this review we searched databases including Medline and google scholar for research articles published between January 2020 and January 2022. We included case reports, case series, cross sectional, cohort, and randomized control trials that reported the duration of shedding of viable SARS-CoV-2 virus. After evaluating the criteria for inclusion, 32 articles (2721 patients) were included.

Result: This review showed that the median for the last day of successful viral isolation was 11 (8.5-14.5 95% CI) , 20 (9.0-57.5 95 %CI), 20 (9.0-103 95 %CI) for the general population, critical patients and immunocompromised individuals, respectively, with significant association between prolonged viral shedding, disease severity (P-Value 0.024) and immunosuppressive status (P-Value 0.023).The corresponding higher cutoff of CTv to culturable virus ranged between 26.25 and 34.00 (95% confidence interval) with median of 30.5, and higher values were observed when critical (25.0-37.37 95 %CI) and immunocompromised patients (20.0-37.82 95 %CI) have been excluded, this deviation did not represent a statistical significance (P-Value 0.997 and 0.888) respectively.

Conclusion: Our review highlights that repeating SARS-CoV-2 viral RNA test solely in recovering patients has no importance in determining infectivity and emphasizes the individualization of de-isolation decisions based on the host factors and a combined symptom and testing-based approaches with the later benefiting most of correlation with recently introduced rapid antigen test. Our finding in the review also opposes the most recent CDC Guidance on shortening isolation duration in term of the last days of viable transmissible virus, therefore caution should be considered when revising such protocols.

Keywords: COVID-19; CTv, Cycle thresholdvalue; Cycle threshold value; Isolation; PCR; RAT, Rapid antigen test; RT-PCR, Reverse transcription polymerase chain reaction; Transmission; Viral culture.

Fig. 1

Prisma Algorithm for database search and article selection.