At least one-third of the world is under some type of lockdown because of the coronavirus pandemic, as governments urge social distancing to stymie the virus’ spread.
That’s because the COVID-19 virus is insidious.
“There’s significant transmission by people not showing symptoms,” Stephen Morse, an epidemiologist at Columbia University, told Business Insider.
According to Robert Redfield, the director of the Centres for Disease Control and Prevention, 25 to 50 percent of people infected with the new coronavirus don’t present any symptoms or fall ill but can still transmit the illness to others.
Redfield on Tuesday told NPR that “we have pretty much confirmed” that “a significant number of individuals that are infected actually remain asymptomatic.”
Some spread with no symptoms
A study out of Japan underscores the number of COVID-19 carriers who show no symptoms. One focused on the Diamond Princess cruise ship that was placed under quarantine in Japan in early February 2020 when it was discovered a former passenger tested positive for the virus.
That study found that 634 out of 3,063 tests administered to quarantined passengers came back positive. It is estimated that about 17.9% of those positive patients showed no symptoms.
The importance of staying home
These studies, Dr. Khabbaza says, underscore the importance of following instructions from government and medical agencies on protective measures like quarantines and social distancing. Given that so many carriers show minimal to no symptoms, it is impossible to know how many people truly carry the virus. This reality makes preventive measures all the more important.
Because the virus can become airborne by respiratory droplets when an infected person coughs, sneezes or talks near you (within six feet) and can be passed by person-to-person contact, social distancing from others regardless of symptoms can help break the chain of transmissions.
That is why the CDC now recommends wearing a cloth face covering in public, especially in places where it’s hard to maintain at least 6 feet of distance between yourself and another person. Cloth face masks are being recommended because we now know individuals with COVID-19 could have mild or no symptoms, while still spreading the virus to others.