CEBU CITY, Philippines—Did you know that individuals with undetected infection of the novel coronavirus, which were prevalent in China, were the infection source of majority of the confirmed cases?
This is the finding of a study conducted by researchers funded by the US National Institutes of Health (NIH).
“A new study shows that simply avoiding symptomatic people will not go far enough to curb the COVID-19 pandemic,” NIH director Francis Collins wrote in his blog posted on the institutes’ website.
According to Collins, researchers have discovered that many individuals can carry the novel coronavirus without showing any of the typical symptoms of COVID-19: fever, dry cough, and shortness of breath.
These asymptomatic or only mildly ill individuals can still shed virus and infect others, the study found.
“This conclusion adds further weight to the recent guidance from U.S. public health experts: what we need most right now to slow the stealthy spread of this new coronavirus is a full implementation of social distancing,” Collins said. “The new study by NIH-funded researchers, published in the journal Science, documents why social distancing may be our best hope to slow the spread of COVID-19.”
He cited a few highlights of the paper, which looks back to January 2020 and mathematically models the spread of the coronavirus within China:
• For every confirmed case of COVID-19, there are likely another five to 10 people with undetected infections.
• Although they are thought to be only about half as infectious as individuals with confirmed COVID-19, individuals with undetected infections were so prevalent in China that they apparently were the infection source for 86 percent of confirmed cases.
• After China established travel restrictions and social distancing, the spread of COVID-19 slowed considerably.
According to Collins, the findings come from a small international research team that included NIH grantee Jeffrey Shaman, Columbia University Mailman School of Public Health, New York. The team developed a computer model that enabled researchers to simulate the time and place of infections in a grid of 375 Chinese cities.
The researchers did so by combining existing data on the spread of COVID-19 in China with mobility information collected by a location-based service during the country’s popular 40-day Spring Festival, when travel is widespread.
“As these new findings clearly demonstrate, each of us must take social distancing seriously in our daily lives. Social distancing helped blunt the pandemic in China, and it will work in other nations, including the United States,” Collins noted.
He then warned that if the pandemic could not be contained, the novel coronavirus could well circulate around the globe for years to come.
“Healthy young people, whose risk of dying from coronavirus is not zero but quite low, might argue that they shouldn’t be constrained by social distancing.” Collins pointed out. “However, the research highlighted here demonstrates that such individuals are often the unwitting vector for a dangerous virus that can do great harm—and even take the lives of older and more vulnerable people. Think about your grandparents. Then skip the big gathering. We are all in this together.” /bmjo