Masks: The Science Behind Our Most Valuable Public Health Tool

At the outset of the COVID-19 pandemic, both the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) did not recommend wearing masks to prevent the spread of the SARS-CoV-2 virus. As the pandemic has raged on, however, these organizations now recommend the opposite. As a result, an increasing number of cities and states within the United States require the use of a mask when in public settings. The shifting guidelines by the CDC and the WHO have caused public confusion concerning the efficacy and necessity of wearing masks.

There are several legitimate reasons why health organizations were initially hesitant to recommend the use of masks. Due to lapses in testing, the initial prevalence of COVID-19 was thought to be low. The lower the prevalence of disease, the lower the risk of community spread. The potential benefits of universal mask recommendations, in this case, do not outweigh the potential disadvantages.

For one, there was not a means of production that could guarantee enough masks could be produced to meet demand. This could lead to instances of hoarding, price gouging, and public panic. Ultimately, this chain of events would have reduced the availability of masks for medical professionals, essential workers, and others who were at highest risk of contraction and transmission of COVID-19.

Additionally, Americans are not culturally conditioned to wear masks. A universal mask recommendation, as we have seen, is an uphill battle. Imagine if this recommendation was put into place when testing was inaccurately showing a low prevalence of disease and when risk of transmission was believed to be low.

Why did the WHO and CDC change their recommendations?

The SARS-CoV-2 virus is a novel pathogen, meaning that it was previously unknown. As a result, the pandemic response must constantly evolve as our knowledge of the virus evolves. As additional reliable testing became increasingly available, the true prevalence of the disease came into focus. The prevalence was not low, as we previously suspected, but widespread, penetrating cities and communities throughout the United States. SARS-CoV-2 was exploding across the United States and the globe.

Furthermore, additional evidence demonstrated that the virus was more easily transmitted than initially suspected. The combination of these factors necessitated a fundamental change in the way we dealt with the virus. The current course was not working. Hence, the WHO and subsequently the CDC issued the recommendations to wear masks to prevent the transmission of SARS-CoV-2.

Why do we need masks?

COVID-19 is primarily transmitted person-to-person through respiratory droplets [1]. Respiratory droplets, laced with the SARS-CoV-2 virus, are expelled from our nose and mouth when we sneeze, cough, and even when we are simply talking. Infection occurs when these infected droplets are inhaled or otherwise contact our mucosal membranes (primarily our eyes, nose, and mouth). The size of these droplets is important. When a droplet is large, it falls to the ground shortly after it is expelled. Small droplets, on the other hand, can survive suspended in the air for long periods of time. Essentially, this allows for aerosolized or airborne spread. While long-range transmission of SARS-CoV-2 remains unlikely, sort range airborne transmission is not only possible, but likely, especially in small, poorly ventilated spaces [1-4].

The airborne spread of SARS-CoV-2 has only become apparent within the last few months. Initial recommendations such as practicing proper hand hygiene and social distancing work well at preventing fomite and droplet spread. However, they will not prevent airborne transmission of the virus. Wearing a mask, on the other hand, can prevent this type of transmission.

Additionally, there is a large amount of asymptomatic and pre-symptomatic individuals who are infected, do not exhibit symptoms, yet are still able to transmit the virus [5-8]. When a person is sneezing, coughing, or otherwise exhibiting symptoms they know that they need to isolate and take the proper precautions to prevent transmitting the virus. An asymptomatic or pre-symptomatic person, on the other hand, does not know that they should be isolating and are proceeding about their days normally, which exposes every person they encounter to SARS-CoV-2.

Masks mitigate the risks of airborne and droplet spread as well as spread by asymptomatic and pre-symptomatic individuals. Facial coverings provide a two-way barrier that both prevents us from becoming infected and infecting others. When healthy, a mask will provide a barrier that prevents the inhalation of infected particles. When infected, a mask will contain the SARS-CoV-2 respiratory droplets and prevent them from being expelled into the air [9, 10]. As demonstrated by the evidence, the wearing of masks can effectively disrupt many routes of transmission.

Is there scientific evidence showing that masks work?

There are numerous studies that have demonstrated the positive effects of wearing a mask [9, 10]. An article published by University of California San Francisco does a fantastic job of explaining the research in an easily intelligible way (you can find the article here)[11]. One study found that the introduction of a mask mandate in 15 states and Washington DC led to a substantial decline in the growth rate of the COVID-19 epidemic, averting more than 200,000 deaths by May 22nd, 2020 [12]. An additional study found that countries with societal norms and governmental policies supporting mask wearing by the public had lower per-capita mortality from COVID-19 [13].

There are also several compelling case reports that describe high risk transmission scenarios where transmission of COVID-19 was prevented by wearing of face masks. In one case, a man flew from China to Toronto and although he exhibited symptoms while on the flight, no secondary infections were recorded [14]. In another, two Missouri hair stylists had close contact with 140 clients while sick with COVID-19. None of these clients tested positive for COVID-19 [15]. The single common denominator—both those afflicted with COVID-19 and those who were susceptible to infection were wearing masks.

What type of mask should I wear and how should I wear it?

There have been several studies that have compared the efficacy of different types of mask materials [16]. In general, surgical masks appear to be more effective than cloth masks at preventing the transmission of COVID-19. Both masks are inferior to N95 masks. There is a great YouTube video that demonstrates how different types of masks work, which you can find here. However, each of the face masks provides additional protection against the virus so long as they are worn consistently and properly. The most important consideration for non-medical personnel should be comfort. This will encourage consistent use of masks and provide protection from COVID-19.

There is a lot of confusion on how masks should be worn. Luckily, we at Intelligent Speculation have produced a short video on the proper way to wear masks. You can find the video here. In short, the mask should sit high on the bridge of your nose and extend below your chin. The mask should fit snuggly across your cheeks and below your chin. Surgical masks should be worn with the blue colored side facing out and be disposed of after a single use. Cloth masks should only be handled by the ear loops in order to prevent fomite transmission of the virus. They should be machine washed and be dried under high heat. Alternatively, they can be hand washed with a bleach solution and air dried. You can find the CDC mask washing guidelines here.

Are there any risks to wearing a mask?

Wearing a mask has significant scientifically demonstrable benefits and has no discernible draw backs. The primary concern of those in the general public is that wearing a mask will in some way inhibit normal breathing. However, there is no evidence to suggest that masks, when worn properly, inhibit normal respiration. There is a useful video showing how masks do not reduce oxygen saturation here. Despite wearing six surgical masks, the physician’s oxygen saturation did not decrease.

Some individuals report discomfort when wearing a mask. Although this is not necessarily a risk of mask wearing, it can certainly be an inconvenience. If you are feeling discomfort, it may be time to try a different mask. There are many variations of effective masks out there. Experiment a bit and I have no doubt you will be able to find one that fits comfortably.

The bottom line…

We are facing an unprecedented global public health crisis. We have exceeded 35 million cases and 1 million deaths globally. Countless lives have been irrevocably altered by this pandemic. Many of these infections and deaths could have been averted if proper public health measures were implemented and adhered to. Unfortunately, those that have been lost cannot be saved. But we can prevent future deaths by following several basic recommendations: practice proper hand hygiene, maintain appropriate social distancing, self-isolate and get tested when exhibiting symptoms of COVID-19, and, yes, wear a mask.

When we think of heroes, we think of billionaire vigilantes or Kyrptonians flying around in red capes. We don’t think of those every day, ordinary heroes. Those who exhibit small, yet important acts of bravery. You can save your family, your friends, and even strangers on the street. You can be a hero. Wear a mask, save a life.