Public health officials continue to urge us all to use face masks, physical distancing and hand washing to reduce the spread of COVID-19. But many individuals seem unconvinced that such efforts are helpful. They point to a lack of scientific evidence on the value of face masks. Two new studies bolster that evidence substantially. There is also informal evidence that support the use of face masks to reduce transmission.
People Who Wear Masks Are Less Likely to Catch COVID-19:
Some people have complained about having to wear masks in public. However, the evidence is increasing that they make a difference. What do we know about the value of face masks?
An Axios/Ipsos Coronavirus Index poll starting in March of 2020 showed that only 11% of those who reported always wearing masks whenever they left home tested positive for COVID-19. On the other hand, 23% of those who rarely or never wore masks tested positive. The poll showed 12% of those who maintained at least a six-foot distance from others tested positive for COVID. In comparison, 20% of people who were less careful about social distancing.
Although masks and social distancing are far from foolproof, they do appear to offer some protection against the transmission of SARS-CoV-2. The variant from India, B.1.617.2, also known as delta, is spreading rapidly in Britain. This variant has also been identified in 6% of COVID cases in the US and will no doubt increase its share in the coming weeks. For those who are not vaccinated, this highly transmissible variant poses a significant risk. Unvaccinated individuals who are not wearing face masks currently may want to reconsider, since the value of face masks is becoming increasingly clear.
Global Research on the Value of Face Masks:
A study published in BMJ Global Health (May 28, 2020) suggests that measures such as washing hands, maintaining distance and wearing face masks do indeed reduce the risk of spreading or catching the coronavirus. Researchers tracked 335 people in 124 families in which one person tested positive for SARS-CoV-2. The goal of the study was to determine how many people in the families caught the virus and if there were any strategies that worked to prevent secondary infection within two weeks of contact.
Almost one fourth of the other family members became infected after contact with one ill member. The risk of transmitting the infection was highest before symptoms developed or early in the disease. This makes isolation or distance much more difficult to use effectively. However, when people in the family wore face masks, washed their hands, disinfected surfaces and used good ventilation, they reduced viral transmission. When people were wearing face masks in the home as a preventive measure before the first family member got ill, other family members were 79 percent less likely to catch the virus. This certainly highlights the value of face masks.
If the initial patient had diarrhea, family members were four times more likely to get sick as well. However, disinfecting the bathroom and closing the toilet lid before flushing were helpful. These could be helpful tactics even after the pandemic has finished.
Another Study on Covering the Face:
A second study published recently confirms the value of face masks. This meta-analysis of 172 studies found that wearing face masks and using eye protection can reduce the risk of contracting COVID-19 (The Lancet, June 1, 2020). Maintaining physical distance between infected and uninfected people was also critical.
Canadian investigators reviewed data collected from more than 25,000 volunteers in 16 countries. The researchers analyzed infection rates of coronaviruses including SARS, MERS and SARS-CoV-2. They found that maintaining at least three feet of distance was better than close contact. The farther away people were from each other, the lower the risk of viral transmission.
In addition, people who used face masks conscientiously were less likely to transmit the infection.
The investigators state that
“Face mask use could result in a large reduction in risk of infection, with stronger associations with N95 or similar respirators compared with disposable surgical masks or similar [reusable 12-16-layer cotton masks]. Eye protection also was associated with less infection.”
Because N95 respirators provide much stronger protection, all health care workers should have access to such protective gear. So should other essential employees and anyone who is at high risk for catching SARS-CoV-2. Moreover, in high-risk settings such as hospitals, goggles or face shields offer an extra layer of protection to bolster the value of face masks.