Just last week, in EID Journal: Influenza Resurgence after Relaxation of Public Health and Social Measures, Hong Kong, 2023, we saw a report on the explosive growth of seasonal influenza in the days immediately following the removal of a 3 year-long mask mandate.
Last spring, after some on social media misinterpreted a January Cochrane study as proving that masks don't work, Karla Soares-Weiser, Editor-in-Chief of the Cochrane Library, issued a statement (see Cochrane Statement On Misinterpretations Of Their Mask Study) clarifying the study's findings.
Since COVID is unlikely to be the last severe pandemic threat we will face, it is important to better understand both the advantages and the limitations of face masks. To that end, yesterday the JAMA Network published a Special Communications on the wearing of face masks during a pandemic.
Due to its length, I've only reproduced the Key Points, Abstract, and Conclusion. Follow the link to read the report in its entirety. I'll have a postscript after the break.
Special Communication Infectious Diseases
October 31, 2023
Masks During Pandemics Caused by Respiratory Pathogens—Evidence and Implications for Action
Shama Cash-Goldwasser, MD, MPH1; Arthur L. Reingold, MD2; Stephen P. Luby, MD3; et alLisa A. Jackson, MD, MPH4; Thomas R. Frieden, MD, MPH1
Author Affiliations Article Information
JAMA Netw Open. 2023;6(10):e2339443. doi:10.1001/jamanetworkopen.2023.39443
Key Points
Question During the COVID-19 pandemic, what has been learned about whether face mask use is associated with lower transmission of SARS-CoV-2 in community settings, and how has it been learned?
Findings Literature review revealed many high-quality observational studies demonstrating the association of face mask use in the community and of mask mandates with reduced spread of SARS-CoV-2. Randomized clinical trials conducted during the pandemic provide limited information.
Meaning Robust available data support the use of face masks in community settings to reduce transmission of SARS-CoV-2 and should inform future responses to epidemics and pandemics caused by respiratory viruses.
Abstract
Importance As demonstrated by the influenza virus and SARS-CoV-2, viruses spread by the respiratory route can cause deadly pandemics, and face masks can reduce the spread of these pathogens. The effectiveness of responses to future epidemics and pandemics will depend at least in part on whether evidence on masks, including from the COVID-19 pandemic, is utilized.
Observations Well-designed observational studies have demonstrated the association of mask use with reduced transmission of SARS-CoV-2 in community settings, and rigorous evaluations of mask mandates have found substantial protection. Disagreement about whether face masks reduce the spread of SARS-CoV-2 has been exacerbated by a focus on randomized trials, which are limited in number, scope, and statistical power.
Many effective public health policies have never been assessed in randomized clinical trials; such trials are not the gold standard of evidence for the efficacy of all interventions. Masking in the community to reduce the spread of SARS-CoV-2 is supported by robust evidence from diverse settings and populations. Data on the epidemiologic, environmental, and mask design parameters that influence the effectiveness of masking provide insights on when and how masks should be used to prevent transmission.
Conclusions and Relevance During the next epidemic or pandemic caused by a respiratory pathogen, decision-makers will need to rely on existing evidence as they implement interventions. High-quality studies have shown that use of face masks in the community is associated with reduced transmission of SARS-CoV-2 and is likely to be an important component of an effective response to a future respiratory threat
(SNIP)
Conclusions
Effectiveness depends on many factors. No public health intervention, even a highly efficacious vaccine, is 100% effective. Even the best masks will not provide complete protection, and benefits of masking are limited if masks are not worn everywhere transmission occurs (eg, health care workers who consistently wear masks while working with patients but not in break rooms with other health care workers or in the community can be infected in the latter settings). In any pandemic or epidemic, masking will be just one of a series of interventions.
The most effective strategies to limit illness and death from SARS-CoV-2 and other respiratory pathogens involve a layered response, including vaccination when available, isolation of infectious people, and protection through risk reduction—including use of high-quality masks in areas and at times and by vulnerable populations when the pathogen may be spreading. The COVID-19 pandemic and the global mpox outbreak are sobering reminders that we will confront new infectious disease threats in the future. Despite new approaches to developing and manufacturing vaccines (particularly mRNA technology) that can reduce the time between pathogen discovery and vaccine availability, that time frame will still be months at best and, for some pathogens, years or decades.
Thus, decision-makers will again need to rely on existing and rapidly generated evidence as they implement interventions to mitigate disease spread. In these circumstances, RCTs and meta-analyses have important limitations and should not form the sole, or even primary, basis of public health decisions.
Available evidence strongly suggests that masking in the community can reduce the spread of SARS-CoV-2 and that masking with the highest-quality masks that can be made widely available should play an important role in controlling whatever pandemic caused by a respiratory pathogen awaits us.
Although there were a lot of mistakes make in the opening months of the pandemic, perhaps the most egregious was the failure to promote the early wearing of face masks by the public. It would take until April 2020 for the CDC to come around, and June for the WHO.
The reason behind this delayed decision was more practical than science based.
We've known for well over a decade that we'd face huge shortages of PPEs (see 2009's Caught With Our Masks Down) during any pandemic, and yet the world did little to prepare. Despite repeated warnings (see 2014's NIOSH: Options To Maximize The Supply of Respirators During A Pandemic) the Strategic National Stockpile's cupboard was no better stocked when COVID hit.
This lack of foresight meant that even some medical personnel were forced to wear makeshift, or inadequate, PPEs. The only good news was that COVID wasn't any deadlier than it was. Had this been a severe avian flu pandemic, the toll could have been much higher.
Today, while supplies are abundant and prices are low, would be a good time to make sure you have an extra box or two of surgical masks, KN95s, or N95 respirators in your emergency kit. This was a recommendation I was making long before COVID emerged, and one I continue to make.
Even if most people don't feel the need to wear them now - during the next public health crisis - they may be much harder to come by.
