What are the prevalence and characteristics of asymptomatic COVID-19 patients?

Bottom Line:

The likelihood that approximately 40% to 45% of those infected with SARS-CoV-2 will remain asymptomatic suggests that the virus might have greater potential than previously estimated to spread silently and deeply through human populations.


Oran, D.P. et al. Prevalence of Asymptomatic SARS-CoV-2 Infection. Annals of Internal Medicine (2020). https://doi.org/10.7326/M20-3012

Date Published:

3 June 2020


A significant portion of COVID-19 patients remain without symptoms, and research is being done to explore their level of infectiousness. Asymptomatic persons can transmit SARS-CoV-2 to others for an extended period, perhaps longer than 14 days. Therefore, the absence of COVID-19 symptoms in persons infected with SARS-CoV-2 might not necessarily imply an absence of harm. The focus of testing programs for SARS-CoV-2 should be substantially broadened to include persons who do not have symptoms of COVID-19. More research is needed to determine the significance of subclinical lung changes visible on computed tomography (CT) scans.

Summary by: David Lee