The duration of infectiousness of individuals infected with SARS-CoV-2

Abstract

Objectives: To summarise the evidence on the duration of infectiousness of individuals in whom SARS-CoV-2 ribonucleic acid is detected. Methods: A rapid review was undertaken in PubMed, Europe PubMed Central and EMBASE from 1 January 2020 to 26 August 2020. Results: We identified 15 relevant studies, including 13 virus culture and 2 contact tracing studies. For 5 virus culture studies, the last day on which SARS-CoV-2 was isolated occurred within 10 days of symptom onset. For another 5 studies, SARS-CoV-2 was isolated beyond day 10 for approximately 3% of included patients. The remaining 3 virus culture studies included patients with severe or critical disease; SARS-CoV-2 was isolated up to day 32 in one study. Two studies identified immunocompromised patients from whom SARS-CoV-2 was isolated for up to 20 days. Both contact tracing studies, when close contacts were first exposed greater than 5 days after symptom onset in the index case, found no evidence of laboratoryconfirmed onward transmission of SARS-CoV-2. Conclusion: COVID-19 patients with mild-to-moderate illness are highly unlikely to be infectious beyond 10 days of symptoms. However, evidence from a limited number of studies indicates that patients with severe-to-critical illness or who are immunocompromised, may shed infectious virus for longer .

Prolonged SARS-CoV-2 cell culture replication in respiratory samples from patients with severe COVID-19

“…Prolonged detection of viral replication has been demonstrated in immunosuppressed patients 14 ; however, our results show that viral replication can also be detected in immunocompetent patients, even with moderate or low viral loads, for longer periods of time than those previously described. 7 , 12 , 15 It remains to be seen whether this finding is related to our higher cell culture positivity rate (51.6%) in patients with severe COVID-19 compared with that reported previously (9%), 7 due to technical factors such as cell line permissiveness to SARS-CoV-2. 16 Ideally, viral viability should be measured in human nasopharyngeal epithelium cell culture.…”

SARS-CoV-2 positive virus culture 7 weeks after onset of COVID-19 in an immunocompromised patient suffering from X chromosome-linked agammaglobulinemia

“…Walsh et al recently published a review in this journal focusing on the duration of infectiousness in SARS-CoV-2 infected individuals. ( 1 ) Based on available data from SARS-CoV-2 culture studies and contract tracing studies included in this review, the authors reported that patients with mild-to-moderate Coronavirus Disease 2019 (COVID-19) are considered to be without infectious potential beyond day 10 after the onset of symptoms. In contrast, immunocompromised and severe-to-critical patients may have prolonged viral shedding and, thus, may also provide prolonged infectiousness.…”

Caution in interpretation of SARS-CoV-2 quantification based on RT-PCR cycle threshold value

“…Among those factors, our study and others highlight the importance of the RT-PCR method used ( Dust et al, November 2020 , Procop et al, October 5, 2020 , Kasteren et al, July 2020 , Zhen et al, April 27, 2020 ). The potential patient contagiousness, evaluated in the foreground on clinical criteria and time from symptoms onset, cannot be determined on the sole RT-PCR Ct result and can also be partly estimated after inoculation in cell culture ( Walsh et al, October 10, 2020 ). If PCR thresholds are given beyond which viral excretion can be estimated as low, they will remain strictly dependent on the technique used.…”