By Michael T. Osterholm
Science, when done well, can be messy, imperfect, and slower than we wish. And it’s ever-evolving. Unfortunately, in the time of a pandemic, we wish this weren’t the case, as we all want and need immediate answers.
Public health policy — including COVID-19 response — should always be informed by the best data available and should evolve with scientific knowledge. But it should not be based on popular opinion or even well-meaning movements within the scientific community. Good science should precede policy, not vice versa.
From the very first cases in China, Center for Infectious Disease Research and Policy (CIDRAP) has been compiling and disseminating science-based information and straight talk on COVID-19. In fact, our dedicated team has been providing science-based, non-partisan coverage of infectious diseases for nearly 20 years. Our only agenda is to inform the public about what the scientific community knows and does not yet know about COVID-19. We take this same approach with cloth face coverings.
At the outset, I want to make several points crystal clear:
I support the wearing of cloth face coverings (masks) by the general public.
Stop citing CIDRAP and me as grounds to not wear masks, whether mandated or not.
Don’t, however, use the wearing of cloth face coverings as an excuse to decrease other crucial, likely more effective, protective steps, like physical distancing.
Also, don’t use poorly conducted studies to support a contention that wearing cloth face coverings will drive the pandemic into the ground. But even if they reduce infection risk somewhat, wearing them can be important.
I’ve received increasing criticism in recent weeks because I’ve offered more nuanced messaging on whether everyone should wear cloth face coverings in public to protect against COVID-19 transmission — messaging that some view as unacceptable. The criticism has included a recent commentary by Masks4All proponents Jeremy Howard and Vincent Rajkumar, MD, that mischaracterizes my position on cloth face coverings and misrepresents the science of personal protection for COVID-19.
Again, I want to make it very clear that I support the use of cloth face coverings by the general public. I wear one myself on the limited occasions I’m out in public. In areas where face coverings are mandated, I expect the public to follow the mandate and wear them.
At the same time, I have been concerned about “message creep” since the Centers for Disease Control and Prevention (CDC) first recommended in April to use cloth face coverings without providing additional context regarding their use. Public health messaging should include a more precise discussion of the effectiveness of cloth face coverings in preventing transmission of SARS-CoV-2, the virus that causes COVID-19. We need to be clear that cloth face coverings are one tool we have to fight the pandemic, but they alone will not end it. And we need to underscore the key role that physical distancing plays — even when you wear a face covering.
Guidance from agencies such as the European Centre for Disease Prevention and Control (ECDC) and the World Health Organization (WHO) make it clear that the use of face coverings in the community should be considered only as a complementary measure to other preventive tools such as physical distancing. They recommend that face coverings should be used as part of a comprehensive strategy, but that the use of a face covering alone is not sufficient to provide an adequate level of protection against COVID-19. A report by the Usher Network for COVID-19 Evidence Reviews (UNCOVER), similarly states that “The lower protective capabilities of a homemade mask should be emphasized to the public so that unnecessary risks are not taken.”
I expressed these concerns in my June 2 podcast episode on masks, saying:
“[The general public] should be made aware that [cloth] masks may provide some benefit in reducing the risk of virus transmission, but at best it can only be anticipated to be limited. Distancing remains the most important risk reduction action they can take. … The messaging that dominates our COVID-19 discussions right now makes it seem that — if we are wearing cloth masks — you’re not going to infect me and I’m not going to infect you. I worry that many people highly vulnerable to life-threatening COVID-19 will hear this message and make decisions that they otherwise wouldn’t have made about distancing because of an unproven sense of cloth mask security.”
These concerns remain true today, particularly after CDC leadership made the unfortunate statement that the U.S. epidemic could be driven to the ground if everyone wore face coverings for the next 4 to 6 weeks. If this were true, why do we need a vaccine to end this pandemic? Just “mask our way” to control. When put into this context, it’s obvious how the CDC statement is unrealistic and misleading. Why do places like Hong Kong, which has a requirement for the use of cloth face coverings in public at a risk of a $HK 5,000 fine, have their highest number of community-acquired COVID-19 cases since the beginning of the pandemic?
In the same June 2 podcast, I further dispelled notions that I’m “anti-mask”:
“I’m working with a group of some of the country’s most renowned technology leaders to develop a reusable N95 mask that could be washed hundreds of times without losing its electrostatic charge and fit … If these masks can become a reality and many, many millions of them made and distributed to the public around the world in the next few months, this could be a real game-changer. So anyone who claims I don’t think masks are important, they are just plain wrong. I do. In fact, I think about it frequently as my daughter, who is a neonatologist, goes to work every day to a potential COVID situation. I think about that all the time.”
We mustn’t overreach what the current data tell us. Authors and journal editors have a responsibility to clearly communicate the limitations of study designs and thus not overstate the results. As consumers of these data, public health officials and academics have the responsibility to assess and critique studies with unfailing rigor.
Let me give just one recent example. A letter last week from three deans of schools of public health that called for universal masking cited just one study on mask effectiveness, yet that study had egregious and much publicized methodologic flaws — so much so that it prompted a call to the journal editor for its retraction from more than 50 subject-area experts. The deans obviously were unaware of this call for retraction and must not have reviewed the study sufficiently to appreciate its critical deficiencies. If we fail to assess studies on cloth face coverings critically, we fall prey to confirmation bias and risk developing policy not based on sound scientific evidence.
In the same vein, we must not conflate the sheer number of recent studies on cloth face coverings with quality. A series of papers have been published in recent weeks addressing the effectiveness of cloth face coverings, but they collectively lack scientific rigor for a variety of reasons, including a much-touted meta-analysis that did not even include studies of cloth face coverings in the community but rather included studies largely on surgical masks and N95 respirators used in healthcare settings.
It is critical that not just more research, but high-quality research be conducted so that the scientific community can assess the effectiveness of cloth face coverings in reducing COVID-19 transmission. Transparency is sorely needed in two areas in particular to help us parse out the impact of cloth face coverings: the setting in which the studies are conducted (e.g., hospital settings vs community-based settings) and whether they assess respirators, surgical masks, or cloth face coverings.
As much as I applaud the spirit of Masks4All, Mr. Howard and Dr. Rajkumar’s commentary does not accurately reflect my and CIDRAP’s perspective on cloth face coverings nor the science of personal protection. Many uncertainties about SARS-CoV-2 remain.
As scientists, Mr. Howard, Dr. Rajkumar, and I will agree, I’m sure, that being truthful about these uncertainties is vital. The public can make good decisions only when officials lay out both the knowns and unknowns. Thus, I think it’s important to address, in some detail, some misstatements and misunderstandings reflected in their article.
Michael T. Osterholm is an American epidemiologist, regents professor, and director of the Center for Infectious Disease Research and Policy at the University of Minnesota.
Credit: CIDRAP newsletter