U.S. Air Force Academy -- (U.S. Air Force photo/Trevor Cokley)

Most public health successes are the results of years of research. Vaccines are a good example; the research needed to develop them can take decades. However, in emergent settings where the luxury of time is absent, resolute action is needed. 

In 1847, when the Hungarian obstetrician Dr. Ignaz Semmelweis realized the necessity of hand washing prior to delivering babies, the maternal mortality rate then fell from 18 percent to below 2 percent. In 1854 the anesthesiologist Dr. John Snow removed a pump handle from the Broad Street pump, and the cholera epidemic in London came to an abrupt end.

Today, we are in a crisis situation with COVID-19. Two of the most effective tools we have to stop the transmission of COVID-19 are physical distancing and masks. Since medical masks are in short supply, the public has been advised to use cloth masks as the primary alternative. It seems like almost weekly, there is more research documenting the effectiveness of facial coverings. These studies range from population based, bench top, mathematical modeling, visualizing respiratory droplets, and meta-analysis

Dr. Michael Osterholm, head of the Center for Infectious Disease Research and Policy at the University of Minnesota (CIDRAP), is one of our country’s top experts on infectious diseases. He has been a strong advocate for the importance of physical distancing. But when it comes to the efficiency of cloth masks, often the most accessible type of protective mask for the public, we believe Osterholm and his CIDRAP colleagues are using their platform to mislead the public.

WCCO radio reported in May that “Coronavirus expert Dr. Osterholm questions guidelines on cloth masks, says they don’t stand up to virus’ air assault.” They quoted Osterholm as saying, “Cloth masks, I think… have little impact, if any.” In another WCCO appearance he stated, “The Minneapolis mask mandate could do more harm than good”. The Cape Charles Mirror had further remarks from Osterholm: “The stupid masks you wear to the store don’t do anything… If you want to wear a cloth mask, use it. Know that I don’t believe, or none of my colleagues, that this is going to have a major positive impact.”

Hard data contradict such claims. In countries with cultural norms or government policies that support public mask-wearing, per-capita cor­­­­­­­­­­­­­­onavirus mortality increased on average by just 5.4 percent each week. That compared with 48 percent each week in remaining countries. Separate analyses of U.S. states and of Google Trends and E-commerce data show much the same. In most of these countries and states, medical masks have been in short supply, and many people have instead used more readily available non-medical masks. 

Even a simple cloth mask is highly effective for stopping droplets on egress. Modeling suggests that universal mask use may limit or halt the spread of the disease.

Osterholm’s onslaught against cloth masks is particularly troublesome because it comes at a time when mask wearing has become highly politicized in the U.S. It offers ammunition to people who want to make wearing face masks a personal choice, or even a political statement, instead of a moral imperative.

Coming from someone who claims that research should be carefully reviewed, it’s surprising that he and his team have not published any peer-reviewed studies about masks for COVID-19. Yet they are widely communicating their views on radio, TV, podcasts, and unreviewed articles on their own web site.

Osterholm used his podcast to broadcast particularly harsh words about a letter urging mask requirements that was organized by two of us. The letter was co-signed by over 100 experts, including two Nobel laureates, the editors in chief of Nature and The Lancet, and professors of biostatistics, infectious diseases, virology, aerosol science, medicine, epidemiology, and other fields. Osterholm’s conclusion was “I hope if nothing else, “so-called” experts on the various issues related to COVID-19 learn to stay in their professional lanes”. 

The letter linked to, and drew heavily from, an evidence review by 19 multidisciplinary authors with over 100 references. It has been submitted for peer review, as well as being published to preprints.org, where it has become its most viewed paper in history — it has received dozens of responses from the scientific community and has been revised based on those responses.

Much of the podcast criticism of the letter, and mask wearing more generally, is based on a misunderstanding of aerosol science. We know that speaking can expel particles. These droplets rapidly evaporate into droplet nuclei, which can remain in the air for 8-14 minutes, a finding consistent with earlier analysis of airborne influenza. The importance of speech droplets as a transmission vector was first discussed in 1934, developed further in 1946, and it is believed that speech plausibly serves as an important and under-recognized transmission mechanism for COVID-19.

There are numerous errors in the podcast which serve to sow confusion in the minds of the public. There are also criticisms directed at the backgrounds of the authors rather than substantive disagreements of the science, such as his criticism of a paper from De Kai et al describing the results of two epidemiological models.

This isn’t an issue that should have two sides. Given the preponderance of data in favor of mask wearing, it seems sensible to promote their usage in addition to continued social distancing and hand washing. Countries that were early to adopt masks (or already had a culture accustomed to wearing masks) have controlled their epidemics more effectively. Collectively, our primary goal should be to find ways to end this epidemic, as Dr. Snow did when he removed that handle from the Broad Street pump. 

The purpose of our article is not to vilify any one person. Our goal is to emphasize the importance of masks, and to point out that entrenched beliefs about the type of data needed to adopt public health measures without regard to the urgency of the situation can cause harm. 

We would also like to see corrections to the CIDRAP website which still makes the claim that “sweeping mask recommendations… will not reduce SARS-CoV-2 transmission”. Furthermore, to prevent inaccurate messaging in the future, we would suggest that CIDRAP authors engage with the wider scientific community through a transparent and open review system for articles published without peer review.

MarkAlain Déry, DO, MPH, FACOI, is the Chief Innovation Officer and Medical Director of Infectious Diseases at Access Health Louisiana, the largest Federally Qualified Health Center (FQHC) in Louisiana with 39 clinics throughout the state. He is a practicing infectious diseases physician, epidemiologist, and hosts a daily 10 minute podcast called NoiseFilter which looks at COVID-19 news through the filter of social, economic and racial justice. 

Contributing to this column: Jeremy Howard, Distinguished Research Scientist, University of San Francisco, and Vincent Rajkumar, Editor-in-chief, Blood Cancer Journal

The Opinion section is a community forum. Views expressed are not necessarily those of The Lens or its staff. To propose an idea for a column, contact Opinion Editor Tom Wright at twright@thelensnola.org.