'The effect is greatest when 100% of the public wear face masks': Growing body of research shows the role of face coverings in curbing the spread of the coronavirus

• Several new studies underscore what health experts have maintained since the coronavirus spread across the globe.
• Face masks help to reduce the highly contagious disease's rate of spread.
• Researchers also stressed the need for preventative measures like social distancing, personal protective equipment, and enhanced hygiene.

Partisanship in American politics has weaponized the face mask while people continue to fall sick and die of the coronavirus.

But a growing body of research shows that wearing face coverings in public can limit the spread of the highly contagious disease, which has infected more than 2 million people in the United States and killed 115,251 as of Saturday, based on data from Johns Hopkins University.

A review and meta-analysis funded by the World Health Organization and published in The Lancet, a peer-reviewed medical journal, examined data from 172 studies from 16 countries and six continents.

Without a mask, the risk of transmitting COVID-19 is 17.4%. With an N95 respirator or face mask, that number drops to 3.1%.

"Our findings continued to support the ideas not only that masks in general are associated with a large reduction in risk of infection from SARS-CoV-2, SARS-CoV, and MERS-CoV but also that N95 or similar respirators might be associated with a larger degree of protection from viral infection than disposable medical masks or reusable multilayer (12–16-layer) cotton masks," the review's authors wrote.

Similarly, maintaining between three and six feet of distance from others reduces the infection rate from 12.8% to 2.6%.

"The main benefit of physical distancing measures is to prevent onward transmission and, thereby, reduce the adverse outcomes of SARS-CoV-2 infection. Hence, the results of our current review support the implementation of a policy of physical distancing of at least 1 [meter] and, if feasible, 2 [meters] or more," according to the review.

Medical experts believe that the coronavirus typically spreads via droplets from a patient's coughs, speech, or sneezes. It's also possible for a person to never show symptoms and yet transmit the disease to others they come in contact with.

So eye protection hasn't been a standard recommendation like regular hand-washing. But the Lancet review found that wearing goggles or a faceshield brings the transmission rate down from 16% to 5.5%.

"The use of a mask alone is insufficient to provide an adequate level of protection or source control, and other personal and community level measures should also be adopted to suppress transmission of respiratory viruses," the WHO said. "Whether or not masks are used, compliance with hand hygiene, physical distancing and other infection prevention and control (IPC) measures are critical to prevent human-to-human transmission of COVID-19."

President Donald Trump's actions, however, continue to fly in the face of these findings. He refuses to wear masks in public and went so far as to poke fun at Democratic presidential nominee Joe Biden for wearing one.

'Symptom-based surveillance might not detect all infections'

Meanwhile, a study conducted by the US Navy's Bureau of Medicine and the Centers for Disease Control and Prevention found that preventative measures also lowered the infection rate among sailors on board the USS Theodore Roosevelt.

The Navy reported that out of a crew of about 4,800 sailors, 1,273 tested positive for the virus and 382 sailors participated in the study.

The results indicated that sailors who did not wear masks experienced an 80.8% infection rate, while those who used face coverings had a 55.8% infection rate. People who did not follow social distancing guidelines fell sick at a rate of 70% versus 54.7% for those who stayed around six feet away from others.

Also, sailors who used common areas reported an infection rate of 67.5% and those who avoided those spaces saw a 53.8% infection rate.

The Navy also reported that 18.5% of those who came down with the coronavirus were asymptomatic — so they did not fall sick at all, but were still contagious — while still others had mild symptoms.

"This study shows young, healthy adults with COVID-19 might have mild, atypical, or no symptoms; therefore, symptom-based surveillance might not detect all infections. Use of face coverings and other preventive measures could mitigate transmission in similar settings," the Navy said in a statement, according to the San Diego-Union Tribune.

These findings were echoed by a British study, led by scientists at Cambridge and Greenwich universities, which concluded that lockdowns alone cannot prevent surges in coronavirus cases and deaths.

"Our analyses support the immediate and universal adoption of face masks by the public," Richard Stutt, who co-led the study at Cambridge, Reuters reported.

Stutt added that masks, social distancing, and other containment measures could be "an acceptable way of managing the pandemic and re-opening economic activity" as companies race to develop a vaccine against COVID-19.

This study appeared in a scientific journal called Proceedings of the Royal Society A, with authors writing that "when facemasks are used by the public all the time (not just from when symptoms first appear), the effective reproduction number, [R value], can be decreased below 1, leading to the mitigation of epidemic spread."

The R value indicates how contagious an infectious disease is. An R value above 1 can trigger exponential growth of a virus, per Reuters. In the case of the coronavirus, studies so far suggest that on average patients infect 2 1/2 other people.

So, the study says, "face mask use by the public could significantly reduce the rate of COVID-19 spread, prevent further disease waves and allow less stringent lock-down regimes. The effect is greatest when 100% of the public wear face masks."

A study that was published by the nonprofit Institute of Labor Economics (IZA) investigated the German city of Jena and arrived at similar conclusions about the efficacy of face masks.

"After face masks were introduced on 6 April 2020, the number of new infections fell almost to zero," the authors wrote, adding that the face coverings were most helpful in curbing the infection rate among people who were above 60 years old.

"We believe that the reduction in the growth rates of infections by 40% to 60% is our best estimate of the effects of face masks . . . We should also stress that 40 to 60% might still be a lower bound," they added.

The study went on to say that masks could have made a more significant impact if they had been used earlier and more widely. It wasn't until April 20 and April 29 that all German federal states made it compulsory to wear face coverings.

"The daily growth rates in the number of infections when face masks were introduced was around 2 to 3%," the study's authors wrote. "These are very low growth rates compared to the early days of the epidemic in Germany, where daily growth rates also lay above 50%. One might therefore conjecture that the effects might have been even greater if masks had been introduced earlier. "