COVID-19: patients with severe/critical illness likely to remain infectious beyond 10 days

  • Walsh KA & al
  • J Infect
  • 10/10/2020

  • Liz Scherer
  • Clinical Essentials
L'accesso ai contenuti di questo sito è riservato agli operatori del settore sanitario italiano L'accesso ai contenuti di questo sito è riservato agli operatori del settore sanitario italiano

As an exception during this period of health crisis, some of the publications mentioned are at the time of writing still in prepublication, undergoing peer review and subject to change. The results of this preprint study should be interpreted with utmost caution.


  • Patients with severe/critical COVID-19 and those who are immunocompromised may continue to shed virus >10 days post-symptom onset (PSO).
  • Current data suggest that patients with mild-moderate COVID-19 are unlikely to be infectious >10 days PSO.

Why this matters

  • Isolation/quarantine longer than 10 days PSO may be warranted for patients with more severe COVID-19 and/or immunocompromised status.

Key results

  • 15 studies (13 SARS-CoV-2 virus culture, 2 contact tracing).
  • Virus culture studies: 5 (223 samples from 493 patients cultured >10 days PSO).
  • Assuming 44% positivity rate, approximately 3% (6) with severe/critical illness had samples with replicative SARS-CoV-2 >10 days PSO.
  • Among patients with mild-moderate illness, the probability of SARS-CoV-2 positivity was
  • 2 included contact-tracing studies:
    • 100 cases, 2761 contacts: attack rate (n=22 cases) was higher among 1818 contacts with exposure 5 days PSO (1.0%; 95% CI, 0.6%-1.6%) vs later exposure (n=0; 95% CI, 0%-0.4%).
    • 269 cases, 472 contacts: combined lab-confirmed, probable secondary cases (n=41) exposed for mean 2.37 (standard deviation, 3.36) days, median 1 (interquartile range, 0-4) day PSO.

Study design

  • Rapid review summarizing current evidence on duration of infectiousness in patients with detectable SARS-CoV-2.
  • Funding: Health Research Board.


  • Few pediatric participants.
  • Low-quality design studies.
  • Inconsistent data reporting.