Four in ten people infected with COVID-19 show no symptoms — but are still potential spreaders of the disease, according to a new study.
The findings, published last week in JAMA Network Open, found that 40.5 percent of people diagnosed with COVID-19 globally were asymptomatic.
However, researchers said this highlights the “potential transmission” of the virus unknowingly, particularly in certain settings.
“Screening for asymptomatic infection is required, especially for countries and region that have successfully controlled SARS-CoV-2,” researchers from Peking University said.
“Asymptomatic infections should be under management similar to that for confirmed infections, including isolating and contact tracing.”
The analysis pooled 95 studies covering nearly 30 million people tested for virus and found that 0.25 percent — or one in every 400 – were asymptomatic. Those figures were higher up among populations in nursing homes (4.52 percent), travelers (2 percent) and pregnant women (2.3 percent), researchers found.
Among confirmed cases of the virus, however, the figure shot up to more than 40 percent. Some 54 percent of pregnant women with confirmed cases were asymptomatic, compared to 53 percent of air or cruise passengers and 48 percent of nursing home residents or staffers, according to the study.
“The high percentage of asymptomatic infections highlights the potential transmission risk of asymptomatic infections in communities,” the study concluded.
The findings show the need for comprehensive COVID-19 testing while people with asymptomatic infections should also go into isolation and undergo contact tracing, Min Liu, a professor of epidemiology and biostatistics at Peking University in Beijing, told UPI.
Research published in also February suggested as many as 44 percent of coronavirus cases were asymptomatic, UPI reported.
“This is a highly important finding because this substantial group of people can transmit the virus to others,” molecular medicine specialist Dr. Eric Topol told UPI in an email.
Topol, director of Scripps Research Translational Institute in La Jolla, California, published similar findings earlier this year, UPI reported.
“It is essential that we have pervasive rapid testing to determine a person’s infectiousness to limit transmission for people without symptoms,” Topol, who was not part of the study, told UPI.