Wearing masks in the time of the novel coronavirus (COVID-19) outbreak — contrary to the World Health Organization (WHO)’s advisory — is crucial in reducing the risk of spreading the virus, two medical experts opined.
George Gao, director-general of the Chinese Center for Disease Control and Prevention (CDC), told Science Magazine in an interview that not wearing masks — a phenomenon currently widely seen in the United States and European countries — during the COVID-19 pandemic is a “big mistake”.
“This virus is transmitted by droplets and close contact. Droplets play a very important role—you’ve got to wear a mask, because when you speak, there are always droplets coming out of your mouth.
“Many people have asymptomatic or presymptomatic infections. If they are wearing face masks, it can prevent droplets that carry the virus from escaping and infecting others,” he said.
Kim Woo-joo, a professor of infectious diseases at the Korea University Guro Hospital and South Korea’s most prominent coronavirus expert, similarly told Asian Boss in an interview on 24 Mar that wearing masks to prevent infection of COVID-19 is “definitely effective”.
“Why else would doctors wear masks in hospitals? They wear them because they prevent infection,” he added, referencing the effectiveness of masks during the SARS and MERS outbreaks.
Professor Kim, who has around 30 years of experience in the area of infectious diseases, said he finds it quite “odd” that not many people wear masks in the West.
“The US Surgeon-General said people didn’t need to wear masks, and WHO recommended people not to wear masks, but I’d have to disagree.
“I did read his tweet … You have to understand the context. I think the point was to prevent the public from hoarding masks, because medical professionals need them more,” said Professor Kim, particularly due to the shortage of masks in the US.
Professor Kim also criticised the WHO’s statement on how people are only encouraged to wear masks in Asian countries due to purported cultural differences, stating that such a view is “problematic” as masks have been “proven” to prevent infection.
“Just look at China, Hong Kong, Japan and Korea … In the meantime, if you look at many European countries and the US, the virus is spreading rapidly. One of the reasons Korea has a relatively low rate of infection is because everyone is wearing a mask and washing their hands regularly,” he said.
Even wearing glasses may help protect a person against coming in contact with droplets carrying the virus, said Professor Kim, as the virus can enter the body through mucous membranes in the eyelids.
“These mucous membranes have a receptor called ACE2. The virus has to stick to those receptors. We don’t have receptors on our skin … Our skin actually acts as a sort of a barrier,” he added.
Professor Kim stressed that while people generally cannot catch the virus simply by breathing — the known routes of COVID-19 transmission are droplet transfer, direct contact and indirect contact with infected persons and surfaces — aerosol or airborne transmission of the virus is still possible.
Citing the Shincheonji church gathering in late Feb — which led to a supercluster in the city of Daegu and an astronomical spike in cases nationwide — Professor Kim said: “Imagine these hundreds of people gathered within one to two metres of each other, praying and singing for hours … If one infected person is present, think about the number of droplets produced.”
“We all spit even when we talk normally. but if you are singing and shouting, you are going to get a lot of droplets. Gravity doesn’t pull all the spit down, which means the droplets don’t land within one to two metres … because the air can also flow sideways,” said Professor Kim, adding that the droplets can travel “much further” than the said distance.
The droplets shrink to less than 5 microns when they dry out, turning into an aerosol that allows them to travel as far as two metres, he said.
“That’s how a person standing quite a few feet away can still get infected,” said Professor Kim.
Airborne transmission in open spaces such as parks, however, is unlikely, according to Professor Kim.
Another South Korean medical expert similarly opined that the risk of aerosol transmission in such regular outdoor environments is low.
Choi Jae-wook, professor at the Preventive Medicine Department of Korea University College of Medicine, was quoted by Korea Biomedical Review as saying that aerosols are usually only formed in specific circumstances, such as “when mucus of a patient comes out from the upper respiratory tract through coughing, or when a patient with a lot of sputum is suctioned or incubated in a hospital”.
“In some patients, upper respiratory tract infections can result in a lot of mucus, causing aerosols,” he added.
WHO’s recommendation on wearing masks only when unwell appears to have been adopted by authorities and certain medical experts in multiple countries, including in Singapore and Malaysia.
The two countries — as well as an increasing number of countries around the world — however, have amped up social distancing measures and border controls to prevent or curb the spread of COVID-19.