From the seasonal flu to the 2003 severe acute respiratory syndrome (SARS) outbreak to the current COVID-19 pandemic, battling respiratory viruses is part of our past, present, and future. These outbreaks and pandemics may vary in length and scale but are similar in that they can cause significant death and illness. Take, for example, COVID-19, which to date is responsible for more than 118 million cases and over 2.6 million deaths globally (1). Canada accounts for nearly 900 thousand cases and over 22 thousand deaths (2). These numbers demonstrate just how infectious some respiratory viruses can be.
The spread of respiratory viruses generally occurs through droplets expelled from an infected individual—for instance, via the nose or mouth when talking, sneezing, or coughing. Therefore, close contact with an infected person or an object containing germs from these droplets can increase the risk of infection (3-5). Efforts to decrease the transmission of respiratory viruses often rely on multiple strategies done in combination with one another. These include: handwashing with soap and water; the use of alcohol based hand sanitizers/rubs; etiquette around coughing and sneezing (e.g., coughing or sneezing into a tissue or the bend of your arm), avoiding touching one’s face, eyes, nose, and mouth; physical distancing; isolation of sick individuals; quarantines; vaccines; and face masks (5;6).
Despite being a widely used practice in certain parts of the world, even in everyday non-pandemic situations, the wearing of face masks has become a controversial issue during the present pandemic. Behind the controversy is the question of whether masks are effective in preventing the transmission of respiratory viruses from one person to another. A comprehensive systematic review looking at the usage of different types of masks (including medical, surgical, and cotton), multiple types of respiratory viruses (influenza, SARS, and COVID-19), and two populations (health care workers and non-healthcare workers) investigated the issue further (3).
What the research tells us
Mask up! The results are positive and lend support to recommendations around mask wearing.
More specifically, the review found that wearing a mask can decrease the transmission of respiratory viruses in both health care workers and non-health care workers. To better understand the results, let’s break them down with numbers. In health care workers, the results translate into an average of 44 less people out of 100 getting infected, compared to no mask use. Even better, in non-health care workers, the results translate into an average of 78 less people becoming infected (3).
Now, do these results mean we can just rely on mask wearing alone? The answer is NO. Mask wearing must be practiced in addition to other public health strategies such as hand hygiene, coughing and sneezing etiquette, physical distancing, vaccines, and so on.
Unfortunately, no comment can be made on which type of mask is most effective amongst those included in the review. However, you can stay up to date on current recommendations by regularly referring to government and public health organizations websites’ or other trusted groups—such as the World Health Organization—for information.
The “do’s” of non-medical face masks
For comprehensive guidance on when the general public needs to wear a mask; materials, construction, and fit; proper use; safety considerations; and answers to other mask-related questions, please visit the Government of Canada's website (7). A few current recommendations include:
- wearing a non-medical mask when in a shared indoor or outdoor space with people outside of your household;
- wearing a non-medical mask that is well-made and provides a proper fit;
- wearing a non-medical mask with multiple layers—such as three-layer mask in which two-layers are composed of tightly woven fabric (e.g., cotton) and one middle layer is composed of a filter-style fabric (e.g., non-woven polypropylene);
- making sure the mask’s materials are breathable;
- washing or sanitizing your hands before putting your mask on, adjusting it, or removing it; and
- keeping your mask clean when it’s not in use or when eating or drinking by placing it in a clean paper or cloth bag until it’s put on again.
