Researchers suggested that people who show severe Covid-19 infection might shed the virus and hence be infectious for as long as 20 days.
Whereas, the infection does not last for more than 9 days in people with mild or no symptoms of the virus.
The review published in the journal Infection Control and Hospital Epidemiology.
A review of dozens of studies by researchers at Oregon Health and Science University and Oregon State University suggests that people may shed virus for prolonged periods.
This is in line with the guidance provided by the US Centres for Disease Control and Prevention, confirming recommendations for the length of time people should isolate the following infection with SARS-CoV-2.
"Detection of viral RNA may not correlate with infectivity since available viral culture data suggests shorter durations of shedding of viable virus," as per the authors.
"Additional data is needed to determine the duration of shedding of viable virus and the implications for risk of transmission."Researchers decided to conduct the review to gain more information on transmission and to help inform infection control practices, said co-author Monica Sikka, MD, assistant professor of medicine (infectious diseases) in the OHSU School of Medicine.
"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 nine days in people who had mild symptoms," Sikka said.
The researchers identified 77 studies worldwide, including 59 that had been peer-reviewed, and combed through the results. All studies reported assessments of viral shedding using standard methods to identify the virus by replicating it through a process called a polymerase chain reaction, or PCR.
"Although PCR positivity can be prolonged, culture data suggest that virus viability is typically shorter in duration," the authors added.