Can COVID-19 be spread by persons who are asymptomatic?

Yes. Certainly, people at greatest risk for spreading COVID-19 are symptomatic people. We need to remember that before symptoms begin, during a period when infected people are “presymptomatic,” they can shed significant amounts of SARS-CoV-2 virus and infect others.

A minority of infected persons never develop symptoms and are classified as “asymptomatic.” These persons still shed virus, but not as much as symptomatic (or presymptomatic) individuals do. It is important to keep in mind that asymptomatic, infected people are more likely than symptomatic persons to be out in public conducting business as usual, in situations where they might transmit the virus to others.

Infected persons without symptoms (both asymptomatic and presymptomatic) look and feel like their usual selves. Any one of us could be infected right now and not know it, which is why it remains critical that we each participate in social distancing, hand hygiene and the use of cloth face coverings in public places where social distancing is difficult. 

*Response provided by David Aronoff, MD, professor and Addison B. Scoville Jr. Chair in Medicine and director of the Division of Infectious Diseases