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Why Should I Wear A Mask? The Science Behind The Wearing Of Facemasks As A Way To Curb The Spread Of Covid-19

Walking on the streets of major cities in Cameroon (Yaoundé, Doula, Buea etc.), you will get the impression that the COVID-19 pandemic is completely eradicated in Cameroon; as most people are seen to move about freely without wearing facemasks or practicing the hand hygiene. Businesses are seen to be fully operational and people go about their activities normally without the respect of the basic measures prescribed to curb the spread of COVID-19. It is clear that lockdown measures as a result of COVID-19 resulted in devastating effects on economic activities in most countries around the world, Cameroon inclusive.  As major towns and cities around the world reopen from stay-at-home restrictions and in an attempt to revive their respective economies, people are required to constantly wear facemasks, observe hand hygiene and practice physical distancing in most public spaces to reduce the spread of COVID-19. But what is really the science behind the wearing of facemasks? Does it really reduce the spread of COVID-19?

Is there evidence that wearing a mask is effective in preventing the spread of COVID-19?

There is quite some evidence supporting the efficacy of masks in preventing the spread of COVID-19. One of such evidence comes from laboratory studies of respiratory droplets and the ability of various masks to block them. In this experiment, high-speed video recording found that hundreds of droplets ranging from 20 to 500 micrometres were generated when saying the simple phrase “stay healthy” but that nearly all these droplets were blocked when the mouth was covered by a damp washcloth.  A different study in which identified seasonal human coronaviruses, influenza viruses and rhinoviruses in exhaled breath and coughs of children and adults with acute respiratory illness found that surgical face masks significantly reduced detection of influenza virus RNA in respiratory droplets and coronavirus RNA in aerosols. Results from this study indicate that surgical face masks could prevent transmission of human coronaviruses and influenza viruses from symptomatic individuals.

Although these laboratory experiments provide good information about on the efficacy of facemasks in preventing the spread of COVID-19, these experiments need to be backed up by real world scenarios where the effective use of masks has been actually worked.  Lyu et al in a community study, found that mandating face mask use in public is associated with a decline in the daily COVID-19 growth rate. Another study looked at coronavirus deaths across 198 countries and found that those with cultural norms or government policies favouring mask-wearing had lower death rates.

Besides these studies, there has been some case reports which suggest the efficacy of facemasks in preventing the spread of COVID-19. In one case, a man flew from China to Toronto and subsequently tested positive for COVID-19. He had a dry cough and wore a mask on the flight, and all 25 people closest to him on the flight tested negative for COVID-19. In another case, in late May, two hair stylists in Missouri had close contact with 140 clients while sick with COVID-19. Everyone wore a mask and none of the clients tested positive.

Who is protected by facemask? The person wearing it or the people around them?

As mentioned above, there is much evidence to show that the wearing of masks best protects people who have COVID-19 from spreading the virus to people who do not have the disease. For those who are not infected with COVID- 19, wearing a mask reduces their chances of getting the infection if they are exposed to the virus. Elsewhere, there is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection or reinfection. This is therefore an indication that both people who have or do not have COVID-19 should wear a mask to reduce the spread of the disease.

The concept of Herd Immunity: How many people need to wear masks to reduce community transmission?

When majority of a population is immune to an infectious disease, this provides indirect protection-or herd immunity (also called herd protection)—to those who are not immune to the disease. For example, if 80% of a population is immune to a virus, four out of every five people who encounter someone with the disease will not get sick (and will not spread the disease any further). In this way, the spread of infectious diseases is kept under control. Depending how contagious an infection is, usually 70% to 90% of a population needs immunity to achieve herd immunity.

There is currently no approved vaccine for COVID 19 hence it is mandatory for everyone to wear masks or at least 80% of the people should put on masks. In one simulation, researchers predicted that 80 percent of the population wearing masks would do more to reduce COVID-19 spread than a strict lockdown.


  • The wearing of masks has been shown to greatly reduce the spread of COVID-19. Therefore the use of masks should be obligatory especially in public places and gatherings. Since economies are opening up and people in some major cities are seen to relax on the wearing of masks, public places that accommodate a small to large group of persons should obligatorily reject entry of persons who have no masks and hand washing stations should be installed at their entry and exit points.
  • Sensitisation messages on the use of masks should focus on why people should wear masks, the kind of protection it confers and published benefits communicated to the public.
  • Wearing masks alone do not prevent you from contracting COVID 19. However, it plays an important role in reducing the spread of COVID-19. It is therefore important to associate the wearing of masks with other recommended measures such as hand hygiene and physical distancing.