Revisiting the Protective Value of Barrier Face Coverings After the COVID-19 Pandemic

Theodore J. Witek Jr, DrPH; James A. Scott, PhD; John R. Balmes, MD


Am J Public Health. 2022;112(6):846-849. 

In This Article

Will we Ever Learn?

After an initial period of wavering, BFCs rapidly emerged as a crucial tool for source control in the pandemic fight, and in the process they became a standard item of daily apparel for most.

This perspective highlights the scientific as well as social rationale for why BFCs should continue to have a role in our postpandemic lives. Perhaps the most compelling reason to keep BFCs at hand stems from our recent experiences with non-COVID respiratory disease infections. In the 2003 SARS outbreak in Toronto, Canada, major spreading events occurred in hospitals, including emergency room waiting areas.[5] In South Korea, the spread of the MERS virus was based in 83% of transmission events attributed to five "super spreaders," and 44% of the total cases represented patients whose exposures occurred in hospitals.[6] Given these experiences, one can easily see the value of requiring patients and visitors to hospitals and clinics, including emergency rooms, to wear BFCs on a default basis. Such low-probability, high-risk transmission events warrant a precautionary approach.[7,8]

We also had to "retake" our failed examination in applied aerosol physics. Specifically, many elements around BFC and respirator use were highlighted as key learnings from SARS in Toronto[5] and from H1N1 in the United States,[9] but these learnings atrophied over the years.[10] Following Canada's SARS outbreak, authorities highlighted the debate on viral transmission mode as a basis to inform the requirements for respiratory personal protective equipment (e.g., N95 respirators). In fact, the debate was not only unhelpful, but likely harmful.[5] This gave way to the strong recommendation in the Spring of Fear report[5] for invoking the precautionary principle without delay in any future outbreak. Unfortunately, these lessons, along with the need for clear and honest communication, were forgotten with the COVID-19 outbreak. The unproductive scientific debate found new oxygen with COVID-19.[11] Rather than accept a somewhat messy scientific continuum of aerosols versus droplet hazard, experts strove for a false dichotomy, and we, once again, suffered for it.

Rather than being immediately forthright that potential medical mask shortages should prompt primary allocation to frontline health workers,[12] mask wearing was initially disclaimed by public health authorities as unnecessary, even harmful, based on the idea that it may exacerbate fomite transmission with the hands near the respiratory and ocular surfaces.[13–15] Within weeks, however, this position was reversed and recommendations to wear masks (or an array of other types of face coverings, including knitted "gators" and flexible plastic shields) was implemented.[14,15] Based on the initial assumption of a primary droplet transmission model, BFCs absolutely should have been mandated much earlier in the pandemic following the precautionary principle. This delay, and the conflicting messaging, undoubtedly contributed to further delays in the adoption of face coverings and may well have contributed to the early case counts.

The lesson here (and epidemiological evidence has since borne it out) is that BFCs substantially reduce SARS-CoV-2 transmission, even in the setting of a disease whose transmission mode is increasingly thought to include smaller aerosols. The preventive efficacy extends to other respiratory illnesses such as colds, flu, and respiratory syncytial virus in children.[7,8] And aside from relatively minor inconvenience, mask wearing seems to have a relatively small downside for most of the population. We suggest a turn to practicality in BFC use after the pandemic emergency subsides.