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  • Mask or no mask? It depends...


    The science is thin whereas the symbolism is strong.

     

    ONE OF THE MORE FASCINATING THINGS that COVID-19 has brought us is a lot of pandemic-related discourse around masks. Wearing a mask seems like a fairly simple, non-invasive and inexpensive intervention to prevent the spread of a virus. Yet the virulence of arguments made on both sides of the issue is so forceful, and, at times, self-confident, it’s worth digging into the evidence to see what lessons we might find partly because I am a firm believer in the adage that all technology bites back.

    I’ll wear a mask when I’m sanding, or when exposed to smoke or dust during a renovation, or when I need to conceal my identity, such as at a costume party or when robbing a bank. Wearing a mask in a crowded place, like a store or a train, while the coronavirus still circulates seems reasonable. Yet in Victoria you see people wearing masks walking alone down the street, riding a bicycle, or even driving alone in a car. Sheesh. Even if there is some theoretical benefit to masking up in some situations, in the process have we lost our common sense? Like many things related to healthcare we think that if a little of something is good, then a lot is better. And we’re probably being misled.

     

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    Wearing a mask in a crowded space during the pandemic seems reasonable. But is there evidence that it makes a difference?

     

    Weakness of the evidence base

    An alert Focus reader from Duncan sent us links to a handful of studies asserting the case that “mandating masks has not kept death rates down anywhere.” The 15 studies he used to support this provocative statement examined health professionals in medical settings over about a 45-year period and he claimed the results have been consistent: “masks are useless in preventing the spread of disease and, if anything, are unsanitary objects that themselves spread bacteria and viruses.”     

    Often in medicine, reasonable-sounding recommendations, when poked, reveal an evidence base that is weak or non-existent. A review of the literature from 2015 of mask wearing in surgery confirmed that there’s very little evidence that “facemasks protect either patient or surgeon from infectious contamination.”

    Just last month researchers Tom Jefferson and Carl Heneghan at the Centre for Evidence Based Medicine in Oxford wrote that in the past three months there have been 15 evidence reviews on masks, but there is still not a single published trial on the effectiveness of masks for COVID-19.

    Let’s not forget that lack of evidence for effectiveness does not mean the contrary is true, that there is evidence for their ineffectiveness. What seems most true is that we simply don’t know.

    Is it possible to extrapolate from other situations, such as studying the spread of other infectious agents, such as the flu virus? In May, an article from the US Centres for Disease Control and Prevention looked at 14 randomized trials of non-drug measures to prevent the spread of the flu. Focusing just on face masks, they found 10 randomized trials of the effects of masks in reducing flu virus infections in the community and found “no significant reduction in influenza transmission with the use of face masks.” 

     

    Shifting public health recommendations

    Earlier in the pandemic, the World Health Organization (WHO) reflected this evidence base, saying that “there is no direct evidence (from studies on COVID-19 and in healthy people in the community) on the effectiveness of universal masking of healthy people in the community to prevent infection with respiratory viruses, including COVID-19.” The WHO went on to state that since the community prevalence of COVID-19 is so low (such as here on Vancouver Island) “even if facemasks are assumed to be effective, the difference in infection rates between using facemasks and not using facemasks would be small.” The numbers, if true, are startling: “Assuming that 20 percent of people infectious with SARS-CoV-2 do not have symptoms, and assuming a risk reduction of 40 percent for wearing facemasks, 200,000 people would need to wear facemasks to prevent one new infection per week in the current epidemiological situation.”

    Even when the evidence case in support of masking shows a pretty small yield, the battle for and against mask wearing remains strong. Spend any time on social media and you’re sure to ingest a powerful dose of pro and anti-mask sentiment. Sidestepping the most vociferous of conspiracy theories, you’ll find those vigorously opposed to lockdowns and physical distancing measures are apoplectic about mandatory mask orders. On the other hand, people in Victoria, whether driven by fear, altruism or simply enacting the spirit of “let’s do what Bonnie asks” can be spotted masked up in the most preposterous of low-risk situations (such as being alone in a car).

    You can’t overlook the symbolism of masks, the wearing of which can be like a talisman, assert virtue and personal support for “doing whatever” to flatten the curve. Alternatively, not wearing one asserts the opposite: that no one is going to restrict my god-given freedom to do whatever the hell I like.   

     

    Stanford scientists on COVID-19 mask guidelines

    Things began to shift in June when the WHO revised their guidelines, after apparently reviewing new information from researchers at Stanford and elsewhere. Claiming that wearing cloth coverings over nose and mouth can prevent the spread of the virus, the WHO guidelines shifted to say that when in close contact with others in crowded areas, with people over 60 or those with underlying health conditions, people should wear medical masks, such as surgical masks, in public.

    This recommendation might pass the test of common sense, noting that masks are just another form of “source control” to prevent the spread of respiratory droplets from infected people. Yet are there any harms in mandating masks? The Stanford researchers quickly discounted a number of arguments put forth that mask wearing can be harmful—curiously presenting no research to support that position—and concluded with a boilerplate platitude: as societies open up more, we need to protect vulnerable people around us and therefore it’s our duty to do what we can.

     

    What if we are all wrong about masks?

    One of the arguments against masks says that wearing face masks can adversely affect attitudes towards social distancing. Which is to say you’re more comfortable sitting or standing closer to someone else when wearing a mask, a case of risk compensation, similar to the argument that people wearing seat belts are more likely to drive recklessly.

    Certainly people with respiratory problems like asthma can find mask-wearing very problematic.

    Then there is the bigger picture about the virus and what is the ultimate effect of hand washing, social isolation and masking policies. Increasingly there is more heft in the discussion of herd immunity, absent a vaccine, and that we’re never going to get through the pandemic until enough of us have been exposed and developed some immunity. Others wonder how high the herd immunity threshold must be before we all basically develop some level of natural protection from the virus. It’s the most crucial unanswered question in this whole pandemic thing.

    Let’s say herd immunity is at 20 percent. That means about 1 in 5 people are immune. If it was this low, the number of people infected would just keep going down. The problem, of course, is that we have no idea where that number is, and whether, ultimately, all our efforts at social distancing and wearing masks are going to make a whit of difference.

    Then there is the big question of how long immunity lasts once people have been exposed to COVID-19 and developed some antibodies. No one knows how long antibodies last or how “protected” one is by previous exposure.    

    We think that wearing a mask is protecting our loved ones, but we may be doing so with a price—prolonging the amount of time we’ll need to get to the other side of this pandemic.

    At the end of the day, no one would argue against an urgent need for scientists to deeply understand COVID-19 and herd immunity before we go overboard with more stringent mask-wearing public policies.

    Heneghan and Jefferson of the Centre for Evidence Based Medicine in Oxford also write that “masks are a symbol for society—[implying that] you are protected. The evidence says you may not be.” They conclude that in this kind of uncertainty, society has a deep responsibility to study the use of masks thoroughly. This can happen a number of ways, especially by examining the many “natural experiments” in different mask and distancing policies around the globe.

    The key is to refuse to jump to premature conclusions such as that tighter masking policies are nothing but beneficial. Only when public health officials are brave and willing to have their preconceptions challenged, can society arrive at a truer understanding of what behaviours are beneficial and which are harmful. Masking might seem like common sense for many people and only time and good research will uncover whether we are being mislead.   

    Alan Cassels is a drug policy researcher and lives in Victoria.

     


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    Guest Change for the better.

    Posted

    Thanks for the well-written and concise article. Given everyone should keep an open mind and read the science first (not politics like we're seeing the US and elsewhere or with the WHO and many other institutions), are you able to share the 15 articles from the Duncan person?

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    Wearing a mask in a borrowed vehicle does not seem unreasonable if the lender apreciates it. Wearing a mask when driving  to pick up elderly parents seems reasonable while we wait for further evidence. Dismissing the behaviour of others without knowing their context seems unkind and heartless.

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    A family physician told me that N95 masks (the best) are guaranteed to filter 95% of particles greater than .3 microns in diameter.  The Corona virus is .1 microns.

     
    (the words in red are done by me for emphasis).  might or possible can also mean might not or possibly not
     
    Conclusion This systematic review found limited evidence that the use of masks might reduce the risk of viral respiratory infections. In the community setting, a possible reduced risk of influenzalike illness was found among mask users. In health care workers, the results show no difference between N95 masks and surgical masks on the risk of confirmed influenza or other confirmed viral respiratory infections, although possible benefits from N95 masks were found for preventing influenzalike illness or other clinical respiratory infections. Surgical masks might be superior to cloth masks but data are limited to 1 trial.

     

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    The article states that there is no direct evidence on the effectiveness of universal masking of healthy people in the community as protection from respiratory viruses.  

    Well, not too worried about healthy people spreading a virus they don’t have. 

    I wear a mask for two reasons. Firstly, if I am not free of a respiratory virus, it may protect others ( you?). Secondly, it is a declaration that I care about my community. That’s not a bad thing in these times and I take pride in that, even as I try to be free of judging those who demonstrate the opposite.
    With a loved one in health care, I know the risk of error. I am happy to do my part.

     

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