When should hospitals require masks?

Is the pandemic over? On the one hand, Covid-19 is clearly still with us. In the U.S., over the past month there was a weekly average of 557 deaths, though the numbers are dropping sharply, from 849 four weeks ago to 208 last week. On the other, for those who are not vulnerable or immune compromised, most facets of life have returned to normal, thanks to high levels of immunity from vaccines, boosters, and past infections.

One of the last vestiges of the pandemic seems to be mask mandates in hospitals, which are now being lifted in the U.S. and Canada to much controversy.

It’s a little strange how much of a lodestone masks have become, because in reality they are a relatively minimal intervention that has few harms and some important benefits. Prior to the pandemic we had little in the way of randomized trial evidence proving specific mask policies worked, but we’ve come a long way since 2020. In the past three years, a great deal of work has demonstrated that masks provide important protections against pandemic respiratory disease, and that community masking programs do indeed reduce the rate of spread. When the evidence changes, it’s important to update your opinions. In some cases, that also means updating practice — like continuing to mask in very specific circumstances, such as when you’re in a hospital and surrounded by vulnerable people.

This ongoing return to normal raises an important question: Are there some public health measures that we should be keeping even though the pandemic itself is on the decline? We believe that requiring masks in hospitals — where the most vulnerable people in society go to get medical treatments — continues to make sense and can protect patients.

There is good evidence that some measures enacted during the pandemic had a clear beneficial effect at a population level. Take health insurance for kids in the U.S. A pandemic-era law helped give kids and families health insurance; with the end of the Covid-19 emergency in the U.S., the law is being lifted, and over 6 million kids could lose health care. This law should be made permanent.

Moreover, we have pre-pandemic studies showing that medical masks are beneficial in hospitals. We also have evidence that better-quality masks, such as N95 masks, have a bigger effect. While population mask mandates are contested — because they require healthy, low-risk people to maintain an intervention long-term even in situations where they may not be at risk for viral transmission — there’s no such argument about health care services.

In any health care setting, particularly in hospitals, many, even most, of the people around you are at high risk from infectious diseases. That’s why many hospitals mandate yearly influenza vaccination for staff, and why you generally have to get a variety of vaccinations before you are allowed to work with sick people. As a recent article published in the Annals of Internal Medicine argued, the use of masks for protection may be one of the “major lessons learned with enduring value” during the pandemic. The authors of this article, who work at the Clinical Center at the National Institutes of Health, say that “for patient safety, it is not time to take off masks in health care settings.”

Of course, that doesn’t necessarily mean that mask mandates in hospitals are something that we need to keep forever. A recent perspective piece pointed out that universal mandates may not be necessary for every health care setting. Masks can cause short-term physical discomfort and may impair communications — and these risks may not outweigh the benefits in every scenario.

But there are scenarios where the benefits of masking in health care settings would outweigh the risks. There are real benefits to reducing respiratory disease transmission, particularly in places where the most vulnerable people go to get help for their health problems. In the health systems where we both work, masks are still required in patient care settings, including clinics and hospital wards.

Nevertheless, as we’ve written before, there is still much we don’t know about public health measures, which combinations of measures, and which sequence of measures worked best at the height of the pandemic. And we don’t know which interventions caused more harm than good. But as we reach the end of the pandemic, it’s clear that some measures, like limits on large venue operations, aren’t needed anymore.

And the cost-benefit equation for a wide range of so-called “non-pharmaceutical interventions” or NPIs, such as masks and physical distancing, has clearly changed now that Covid-19 is much less severe than it was in 2020, the era before vaccines and antiviral medicines. However, NPIs can still play an important role in some situations. There’s a whole range of infectious diseases that masks help to prevent, many of them big killers in the years before our world was turned upside down by Covid-19. If we can reduce the likelihood of people getting influenza, Covid-19, and other infections in hospitals, that alone might be sufficient incentive to continue masking in places where there are vulnerable patients.

We fully understand the desire to put the pandemic behind us. And we appreciate that in some countries, especially the U.S., NPIs have been caught up in culture wars and partisan fights. But if research shows that NPIs can save lives in some situations even when a pandemic has receded or ended, we should not ignore the evidence.

It may be the case that universal mask mandates in hospitals are not entirely beneficial all the time, but that they have a huge impact during winter when viral transmission is at its peak. It may turn out that even during viral surges, masking in low-risk settings such as at large outdoor events is not useful, but that there are major benefits in places where the sickest patients attend, like dialysis wards or radiotherapy clinics.

As the pandemic wanes, it is becoming more and more important that we assess the benefits of the measures we took. We believe it’s important to acknowledge that masks do have some costs, particularly for certain people. But it’s also true that they also save lives.

The guiding question now should be: Where do masks save enough lives to justify their costs? In fact, it’s a good principle to use more broadly when deciding what public health practices we should keep in a Covid-endemic world: When does an intervention save enough lives to justify its costs?

Gideon Meyerowitz-Katz is an epidemiologist from the University of Wollongong and a science writer and communicator. Gavin Yamey, M.D., MPH, is the Heymowitz professor of global gealth and a professor of public policy at Duke University. He directs Duke’s Center for Policy Impact in Global Health.