As cases of the coronavirus accelerate in the United States, more state and local governments are requiring masks in public. While most Americans seem to be in favor of wearing a mask, according to a recent Pew Research poll, there’s still considerable resistance to the universal use of face coverings in public.

Part of the confusion around wearing a mask comes from contradictory messages between public health officials and some political leaders, including President Donald Trump who has refused to wear a mask in public.

How scientists test face mask effectiveness against coronavirus

In a briefing Monday, New York Gov. Andrew Cuomo urged Trump to sign an executive order mandating the use of masks nationwide. Yet, even a national requirement might not persuade some Americans.

“Even if you mandate and people are mandating them, I don’t think it’s necessarily going to convince people really or even force people to wear them. We need to convince, as opposed to compel or mandate,” Dr. Craig Spencer, director of global health in emergency medicine at Columbia University Medical Center told NBC News.

In the early days of the pandemic, cloth face masks weren’t universally endorsed, even by public health experts.

“One, we didn’t know whether they were actually helpful, and two, there was a lot of concern that if people were using medical masks then people like myself, were not going to have access to them,” Spencer said.

The World Health Organization only embraced face coverings for non-healthcare workers in early June, saying that in areas where the virus is spreading, people should wear fabric masks when social distancing is not possible, such as on public transportation and in shops. Mask wearing, which has a long history in Asian nations, might be one reason they are faring much better in controlling the virus, in addition to a more robust contact tracing system.

Still, the change in messaging over masks shouldn’t be seen as a flaw, but as the nature of science, Dr. Jeremy Faust, an emergency physician at Brigham and Women’s Hospital, said.

“That is what experts, in fact, do. They don’t just have an opinion and stick to it,” he said. “They actually let their opinions develop and evolve as better information becomes available.”

What the science shows

As more has been learned about the asymptomatic spread of COVID-19, there has also been a growing body of evidence showing just how effective masks can be.

The new coronavirus is spread by respiratory droplets when an infected person coughs, sneezes or talks. If not blocked by a face covering, the droplets are thought to travel about 6 feet through the air.

In a lab study published May 21 in the New England Journal of Medicine, researchers found that nearly all droplets generated by speaking and talking were blocked when the mouth was covered by a damp washcloth. In another experiment, scientists examined over 100 individuals with a respiratory infection and looked at breathing samples of some who wore a mask and some who didn’t. The research, which was published in Nature, found that masks reduced the detection of respiratory viruses in both droplets and aerosols.

And Tuesday, researchers from Florida Atlantic University found that although all face coverings reduced large droplet transmission to an extent, some were more effective than others. Researchers tested many types of masks on mannequins and simulated how the masks would affect droplets emitted during a cough or a sneeze. The new study showed that well-fitted homemade masks with multiple layers of fabric, as well as off-the-shelf cone style masks, were the most effective in reducing droplet dispersal. Bandannas turned out to be the least effective in reducing transmission.

Other studies have examined how the virus behaves in the real world.

An analysis of 172 studies, with data from SARS, MERS and COVID, showed the chance of transmission of an infection was significantly reduced when a mask was worn. The authors of the analysis, which was funded by the World Health Organization and published in The Lancet in June, cautioned, however, that the certainty of the evidence was “low”.

Recently, researchers from the University of Iowa College of Public Health published a paper in the Journal of Health Affairs examining at the effects of mask mandates. They looked at states which required masks in public and estimated that as many as 230,000–450,000 COVID-19 cases were possibly averted by mandating face coverings.

Sources : NBC News


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