On Oct. 20, 2020, researchers at Oregon Health & Science University (OHSU) and Oregon State University (OSU) reported that a review of dozens of studies suggested that people may shed virus for prolonged periods, but those with mild or no symptoms may be infectious for no more than about 10 days. People who are severely ill from COVID-19 may be infectious for as long as 20 days.

The researchers identified 77 studies worldwide, including 59 that had been peer-reviewed, and combed through the results. The review was published in the journal Infection Control and Hospital Epidemiology.