Patients with Severe COVID-19 Could be Infectious for Up to 20 Days

Patients with mild or no symptoms of COVID-19 may be infectious for just 10 days.

A review of dozens of studies has confirmed the CDC guidance about infectivity of coronavirus disease 2019 (COVID-19), specifically that people with severe COVID-19 may be infectious for as long as 20 days.

The review, published in Infection Control and Hospital Epidemiology, is in line with CDC recommendations for how long people should isolate following a COVID-19 diagnosis. According to the review, patients with mild or no symptoms may be infectious for no more than 10 days, unlike their severely ill counterparts.

“Detection of viral RNA may not correlate with infectivity since available viral culture data suggests shorter durations of shedding of viable virus,” the authors said. “Additional data is needed to determine the duration of shedding of viable virus and the implications for risk of transmission.”

The team identified 77 studies globally, including 59 that have been peer-reviewed. All of the studies reported assessments of viral shedding using standard methods to identify the virus by replicating it through polymerase chain reaction. According to study co-author Monica Sikka, MD, the investigators conducted the review in order to help inform infection control practices.

“Even though people can shed virus for a prolonged period of time, the studies we reviewed indicated that live virus, which may predict infectiousness, was only detected up to 9 days in people who had mild symptoms,” Sikka said in the press release.


Evidence review confirms CDC guidance about infectivity of novel coronavirus [news release]. EurekAlert; October 20, 2020. Accessed October 23, 2020.

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