Why masks still matter | time

DDuring the COVID-19 pandemic, masks have been armed for partisan purposes. “Politicizing mask use,” says William Hanage, an infectious disease epidemiologist at Harvard University, “makes as much sense as politicizing gravity.” Masks are simply a device — a protective barrier — that can help limit the spread of respiratory infections just as condoms are a barrier that can reduce the spread of sexually transmitted infections. And as we head into winter, with rising rates of multiple respiratory viruses, including the flu, RSV and new coronavirus variants, masks could help all Americans avoid illness.

Mask use is on the decline in the United States. Recent public polls show that nearly two-thirds of Americans never or rarely wear a mask outside their homes, a sharp increase from just a quarter during the peak of the Omicron wave in January 2022. There are many reasons for the decline in mask requirements. These include pandemic fatigue, a valid perception that the worst of the COVID-19 pandemic is behind us (there has been a sustained decline in daily COVID-19 deaths), widespread COVID-19 vaccination (80% of Americans now have at least one dose of vaccine), reduced federal and state efforts to provide free high-quality masks to the public, and the lifting of mask requirements.

Despite these trends, it’s important for the public to know that communal masking can help prevent the spread of a range of respiratory infections. The Centers for Disease Control is finding that flu hospitalization rates are higher than usual for the time of year, an added impetus to encourage mask use. A useful analogy is to think of masks as umbrellas, says Simon Nicholas Williams, a lecturer in psychology at the University of Swansea in Wales. If it rains or rain is forecast, we take an umbrella with us. “But just like we don’t have to carry an umbrella when the sun is shining,” he says, “we don’t have to wear masks all the time.”

Transmission of respiratory diseases can be broadly divided into spread by droplets larger than 5 microns, which fall quickly to the ground, and aerosols, smaller than 5 microns, which can remain airborne and inhaled for hours. The science of such transmission suggests that any viruses and bacteria spreading through these pathways should be similarly stopped by mitigation measures that largely target these pathways — including quality masks like N95 or KN95s that cover both droplets and Block aerosols.

Read more: Universal Masking in Schools Works. New data shows how well

Data on the effectiveness of masks in preventing respiratory infections predates COVID-19. During the SARS outbreak in 2003, studies showed that using face masks likely reduced transmission. For example, a study of transmission of SARS from five Hong Kong hospitals, where staff were exposed to infected patients, found that staff who reported using masks were less likely to be infected. But even during SARS, there were signs that mask upgrades could be important. A breakout from a Hong Kong hospital in which unidentified cases were transmitted to healthcare workers wearing only surgical masks showed the relevance of quality masks like N95.

Data on the transmission of tuberculosis in healthcare are also revealing. Irregular use of N95 respirators among Brazilian health workers has been associated with a higher risk of latent tuberculosis (where someone harbors the bacteria but is in a dormant state and is at risk of becoming active later). In addition, other airborne pathogens, such as a bacterium called Coxiella burnetti, which spreads from animals to humans and causes the disease Q fever, have caused outbreaks that were stopped directly by the use of N95. During the COVID-19 pandemic, the use of N95 masks had the added benefit of reducing the transmission of other airborne pathogens, including tuberculosis.

Which type of mask is sufficient depends on the pathogen in question and whether it is better transmitted by air or by larger respiratory droplets. Studies on RSV, for example, found that while this pathway is detectable in aerosols, it is unlikely to be efficient, meaning N95 caliber masks are not required. However, given that we are now facing a simultaneous increase in multiple respiratory viruses at once – including influenza, RSV and COVID-19 – masks that block both pathways are preferable.

Currently, the CDC does not list masks for flu prevention for Americans. And in the past, data has been mixed about what kind of mask would really be needed. A randomized study examining whether the use of N95 respirators versus medical masks was found in the prevention of influenza among healthcare workers found no significant difference. However, the study was mainly conducted in ambulance settings, which are significantly different from those in a hospital, or in a crowded public environment for long periods of time. In another randomized study, use of N95 masks was associated with significantly lower rates of respiratory illness and lower bacterial colonization of the airways. Additionally, efforts to contain COVID-19 over the past two seasons have very likely contributed to exceptionally low influenza transmission, as determined by the CDC. Since the flu is less transmissible than COVID-19, the Community masking level The value required for a blunt transmission would probably be lower and more easily achievable. Given the limited but mixed data, it would be prudent to exercise caution and side with masking in high-risk, crowded public settings where these diseases are most likely to spread.

What the COVID-19 pandemic has made clear is that we need more resilient data to understand many aspects of public masking, including how effective masks will be in preventing other respiratory viruses. While masking effectiveness differs depending on the type of mask and the material used and how the mask fits, it is also affected by when and where masks are used and how consistently. In healthcare, as physicians, we consistently use N95 respirators in rooms of patients with airborne diseases because we know they reduce inhalation of infectious aerosols, which reduces the likelihood of us getting sick. This basic principle applies in a sick room as well as in a crowded bus or grocery store.

Getting vaccinated against the flu and COVID-19 is the most important step you can take to prevent serious illness from these diseases. Unfortunately, there is no approved RSV vaccine, although there is a vaccine candidate for infants that is showing promising results. Even with the vaccines we have, although we will continue to be hit by respiratory viruses every year, the COVID-19 pandemic should remind us that we have a means to reduce the spread through the use of quality masks. Masks will likely help reduce the spread of several viruses and some bacteria — and while more data needs to be generated to understand how best to improve our community-level efforts, we already have enough to tell us that we should mask up this season.

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