SGEM#309: That’s All Joe Asks of You – Wear a Mask

Date: November 25th, 2020 Guest Skeptic: Dr. Joe Vipond has worked as an emergency physician for twenty years, currently at the Rockyview General Hospital.  He is the President of the national charity Canadian Association of Physicians for the Environment (CAPE), as well as the co-founder and co-chair of the local non-profit the Calgary Climate Hub, and during COVID, the co-founder of Masks4Canada. Joe grew up in Calgary and continues to live there with his wife and two daughters. Reference: Bundgaard et al. Effectiveness of Adding a Mask Recommendation to Other Public Health Measures to Prevent SARS-CoV-2 Infection in Danish Mask Wearers: A Randomized Controlled Trial. Annals of Internal Medicine 2020 Case: : Alberta is the last province in Canada that has yet to enact a mandatory mask policy. Should they do it? Mask4All Debate Background: During a respiratory pandemic, there still remains substantial questions about the utility and risk of facial masks for prevention of viral transmission. We debated universal mandatory masking back in the spring on an SGEM Xtra episode. Some very well known evidence-based medicine experts like Dr. Trisha Greenhalgh were advocating in favour of stricter mask regulations based on the precautionary principle (Greenhalgh et al BMJ 2020). She was challenged on her position (Martin et al BMJ 2020) and responded with an article called: Laying straw men to rest (Greenhalgh JECP 2020). A limitation of science is the available evidence. SARS-CoV-2 is a novel virus and we did not have much information specifically about the efficacy of masks. We needed to extrapolate from previous research on masks and other respiratory illnesses. However, we do have a firm understanding of the germ theory of disease and masks have been used for over 100 years as an infectious disease strategy. It was surgeons in the late 1890’s that began wearing masks in the operating theaters. There was skepticism back then as to the efficacy of a “surgical costume” (bonnet and mouth covering) to prevent disease and illness during surgery (Strasser and Schlich Lancet 2020). There was one recent cluster randomized control trial  looking at surgical masks, cloth masks or a control group in healthcare workers (MacIntyre et al BMJ 2015). The main outcomes were clinical respiratory illness, influenza-like illness and laboratory-confirmed respiratory virus infection. All infectious outcomes were highest in the cloth mask group, lower in the control group and lowest in the medical mask group. As with all studies this one had limitations. One of the main ones is this looked at healthcare workers wearing a mask as protection not in the general public as a source control. There has been a systematic review meta-analysis on physical distancing, face masks and eye protection to prevent SARS-Cov-2 (Chu et al Lancet 2020). With regards to masks, they found that face masks could result in a large reduction in risk of infection with a stronger association with N95 or similar respirators compared with disposable surgical masks or similar cloth masks. SRMA also have limitations and one of the main ones is they are dependent on the quality of the included studies. This review in the Lancet included ten studies (n=2,647) with seven from China, eight looking at healthcare workers (not general public) and only one looking at COVID19. All 10 studies were observational designs and the authors correctly only claim associations. They also say their level of certainty about masks being associated with a decrease in disease is considered “low certainty” based on the GRADE category of evidence. When considering an intervention, we cannot just consider the potential benefit, but we must also consider the potential harms. There is little or no evidence that wearing a face mask leads to potential harms. Yes, there are case reports of harm, children under 2 years of age should not wear face coverings (AAP News) and studie...