After a pandemic it is important to look at the measures that were implemented to protect the population and evaluate their effectiveness. Especially with a disease such as COVID-19 that results in a long-term condition in up to 10% of infected people, strict prevention measures might be reasonable if they prove to be effective. In this blog, the effectiveness of mask protection will be discussed. In an upcoming blog, we will address the benefits of social distancing for infection prevention but also the harms of isolation. Research over the past few years has shown that wearing masks greatly helped in reducing the spread of COVID-19. However, there are some rather paradoxical effects associated with this intervention.
Masks are effective in reducing transmission of respiratory viruses
While wearing masks decreases transmission rates, a decrease in disease rates can lead to a lower willingness to wear masks, potentially leading to an epidemic resurgence. The COVID-19 pandemic taught us that using masks in large numbers, also known as mass masking, is not only for self-protection but also helps protect others from potentially harmful respiratory droplets. Even from people who do not show symptoms. If everybody wears a mask to protect others, they are in return protected themselves through the generally lowered transmission rate. Although specific trials on mass masking are scarce, scientific reasoning supports its effectiveness against viruses like the flu and SARS-CoV-2. There were some concerns that mask-wearing might make people feel overly secure and cause them to overlook other preventive measures such as social distancing and handwashing. However, no scientific evidence suggesting that mask-wearing led to this neglect during the pandemic has been reported.
Masks only work as a community measure
A second paradoxical effect of mass masking at a population level is that although wearing a mask may not prevent a single individual from being infected, the transmission within a society is drastically reduced if everybody wears masks. The actions that are only moderately helpful to individuals become significantly beneficial for the whole community. Achieving a significant reduction in virus spread through community mask use therefore relied on the majority of people adopting this practice.
Masks work hand-in-hand with social distancing and handwashing, especially during lockdowns, to stop the spread of the virus at its source. Some countries, like South Korea and Hong Kong, have successfully controlled COVID-19 without lockdowns, mainly through widespread mask usage. We have learned that mass masking is a cost-efficient way to shift the focus from self-protection to community protection, demonstrating global unity during the pandemic.
People who trust science are more likely to use masks correctly
A systematic review of 31 studies, found that in studies where both sick and healthy individuals living together in a household wore masks, the transmission of respiratory illness dropped by 20%. The protection was not similarly strong when only the healthy or only the infected persons wore a mask. However, randomized trials might not be the most reliable evidence for mask effectiveness since participants often do not follow instructions.
Some studies also suggested that people who trust science are more likely to use masks correctly. Following preventive measures, such as limiting social activities and doing self-testing, requires everyone to do their part. But if people do not understand or agree with the proposed measures, they are less likely to follow them which can make them less effective.
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