Getting acceptance for public health actions has historically been difficult. For example, during the 1910 Manchurian Plague, Dr. Wu Lien Teh realized the microbe spread by air and that a simple cotton mask could reduce transmission. But many doctors didn't believe him.
A prominent French doctor mocked Wu and his mask advice. He visited the sick without wearing a mask to prove his point, and died several days later. The plague was indeed contagious and transmitted through the air. The tide turned. For years later, masks were widely used to fight respiratory infections worldwide. But with few respiratory pandemics in the Western world, the lessons were gradually forgotten. Now we need to relearn them.
We are two of over 100 signatories — including a Nobel laureate virologist, the editors in chief of Nature and The Lancet, and many of the world’s leading medical and scientific experts from universities such as Harvard, MIT, Stanford and the University of Texas — of an open letter being sent to all U.S. governors that asks them to "require cloth masks to be worn in all public places, such as stores, transportation systems, and public buildings."
Last week, a group convened by the Royal Society, chaired by Nobel laureate Venki Ramakrishnan, published an evidence paper recommending the use of face masks in the United Kingdom.
Confusing messaging should stop
Even with such strong messages from so many of the world’s top experts, some may still have doubts. Some of this confusion is understandable. Until recently, there has been confusing messaging from many top public health authorities.
Many scientific papers, including one by the authors, have been published recently supporting the efficacy of face coverings for "source control" — that is, stopping an infected person from passing on infection to others. Simple cloth masks appear to stop over 90% of the droplets that transmit the virus. This is crucial, because research suggests that nearly half of infections are spread by people who don’t even show any symptoms, and thus they probably don’t know they’re ill. They can go out and inadvertently spread the virus.
Cloth masks provide some protection to the wearer. But the primary role of mask wearing is to protect others. It stops people from infecting others. It also reduces the viral load if an infection does occur, which likely cuts the risk of a severe illness or death. But to be truly effective, they need to be worn by almost everyone. Recent modeling suggests that we need at least 80% of the population wearing masks to stop the spread of the virus.
To make that happen, just "urging" their use is not enough. We can see this in recent survey results showing thatin majority of states that do not require masks, fewer than halfthe population are using them.
When Republican Gov. Larry Hogan announced a mask requirement in Maryland, he noted that some say this "infringes on their rights." But "it’s about protecting your neighbors," he explained. "People might not know that they're carriers of the virus and … they could infect other people."
We have many laws that primarily protect others, such as laws barring drunken driving and placing limits where people can smoke in public. If it is reasonable to protect people from secondhand smoke and drunken drivers, it is surely reasonable to protect them from a virus that has already killed nearly 84,000 Americans.
Today, the importance of wearing masks is greater than ever. Many regions are easing some of the early restrictions, and there is a debate about the timing of such moves. However, that’s a false dichotomy.
Masks can save American lives
The economy cannot rebound until people feel safe, and people will not feel safe until the outbreak is under control. In a recent CBS News poll, less than a third of people said that they’d feel comfortable going to a bar or restaurant even if restrictions were lifted, and only 15% felt comfortable getting on an airplane. Mobility data shows people are choosing to avoid going out if they can help it regardless of the "open" or "closed" status of a state.
The focus has to remain on confronting this epidemic through a variety measures, including social distancing whenever possible, mass testing, contact tracing, isolation and, yes, crucially wearing face coverings — especially indoors in public places. If there is another major outbreak, confidence will plummet even further.
Our research shows there are no countries that have had near universal mask use since early in the pandemic that have over 1,000 known COVID-19 deaths. If masks led to worse outcomes, we would see it in some of the over 90 countries that now require masks.
Instead, we see that Hong Kong, which has widespread mask use, has had only four confirmed deaths related to the coronavirus. Health authorities there credit mask use as a major contributor to this outcome.
In the United States, we should not accept the horrific death rates we’re seeing in many parts of the country. The science is clear. To save American lives and jobs, we need to fully deploy this powerful tool as widely as possible.
Jeremy Howard is a distinguished research scientist at the University of San Francisco and led an international cross-disciplinary review of the scientific research on masks by 19 medical and scientific experts. Zeynep Tufekci is an associate professor at the University of North Carolina at Chapel Hill and a faculty associate at the Harvard Berkman Klein Center for Internet and Society. Follow them on Twitter: @jeremyphoward and @zeynep