The issue of masks was undoubtedly one of the most controversial during the Covid-19 pandemic and after. Do masks do anything or not? The researchers have now presented a new general study. The result is very clear: yes.
It was and is the subject of heated debate: the question of whether masks can prevent the spread of the coronavirus, or not. A team led by New York scientist Shama Cash-Goldwasser has published a new overview study. The researchers analyzed several high-quality observational studies. The result: masks can limit the spread of the coronavirus. “The available data support the use of masks in the population to reduce the transmission of SARS-CoV-2,” the researchers write.
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According to the study, these findings should serve as a basis for addressing epidemics and pandemics caused by respiratory viruses in the future. “The effectiveness of the measures will depend, at least in part, on whether lessons learned from the Covid-19 pandemic are used. High-quality masks that are widely available could also play an important role in containing pathogens in future pandemics,” the researchers wrote. .
Available data supports the use of masks in the community to reduce transmission of SARS-CoV-2
Shama Cash-Goldwasser | Lead author of the new general study
Masks tested on planes, in schools and at home.
The researchers analyzed several observational studies on the effects of masks on airplanes, in schools, and in household and community contacts. An outbreak of Covid-19 on the aircraft carrier USS Theodore Roosevelt at the beginning of the pandemic, before crew members could develop immunity, was instructive, they say. “More than 80 percent of those who said they did not wear a mask were infected,” the scientists write. “In contrast, those who said they wore a mask were 30 percent less likely to become infected.” Since people on board ships often live together in confined, poorly ventilated spaces for long periods of time, there is generally a high risk of respiratory disease outbreaks.
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Mask type and fit affect transmission
However, scientists admit that even the best masks do not offer complete protection. The effectiveness depends on many factors. “The benefits of wearing masks are limited if they are not worn in all places where transmission occurs.” For example, healthcare workers who constantly wear masks when working with patients could still become infected (if they remove their mask) during breaks or during conversations with colleagues. Additionally, both the type of mask and the fit are crucial to its effectiveness.
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Conceptual mask tested in the laboratory
According to the study, laboratory studies have shown that masks can fundamentally reduce infectious respiratory droplets and aerosols. Human breathing was simulated and the use of cloth masks, surgical masks and N95 respirators was tested using various techniques. “The reduction in droplet and aerosol spread is greatest when both the source and the exposed person are masked,” the researchers write. According to the study, N95 respirators have the highest filtration performance. They have been shown to provide the best protection against coronavirus transmission.
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Study classification.
The overall study “Masks during pandemics caused by respiratory pathogens: evidence and implications for action” analyzed several individual studies, so-called observational studies. In these studies, the conditions are not influenced by the researchers. In contrast, randomized controlled trials (RCTs) work with an experimental group and a control group that uses placebos.
However, in their overall analysis, the researchers led by Shama Cash-Goldwasser intentionally focused “only” on the observational studies published so far. “RCTs and meta-analyses may have significant limitations and should not form the sole, or even primary, basis for public health decisions,” the researchers wrote. “These studies are by no means the gold standard for demonstrating the effectiveness of all measures.” On the contrary: Disagreement over whether masks reduce the spread of the coronavirus has increased due to the attention paid to randomized studies. Unfortunately, these are “limited in number, scope, and statistical significance,” the researchers explain in their approach.
What are observational studies?In an observational study, a group of people are observed over a period of time without the researchers directing or controlling the conditions. This also includes many studies that look at the effects of certain medications or measures in the real world. Often the problem is that external influences, so-called intervening factors, can never be ruled out with 100% certainty. Many experts, for example from the Health Foundation, believe that randomized controlled studies have greater evidence. On the one hand, the influencing factors are carefully controlled and, on the other, there are comparison groups. These randomized controlled studies are not always possible. Among other things, there are ethical considerations: for example, it is considered unacceptable to intentionally expose study participants to cigarette smoke to investigate the effect on cancer development.
What do the latest studies say?
Only in June of this year did the study “Physical interventions to interrupt or reduce the spread of respiratory viruses” by the renowned Cochrane research network cause a stir. Among other things, it states: “The use of masks in the population probably has little or no influence on the occurrence of flu-like illnesses or COVID-19 compared to not wearing masks.”
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Mask opponents interpreted this statement to mean that masks do not protect against coronavirus infection. The Cochrane Research Network immediately commented: “Most studies are older and concern the transmission of influenza and other cold viruses; studies on the corona pandemic remain in the minority.” And in the study itself, the researchers noted: “The risk of bias in RCTs and cluster RCTs was generally high or unclear.”
Most studies are older and concern the transmission of flu and other cold viruses; Studies on the coronavirus pandemic remain a minority
Cochrane Network statement on their study in June 2023
The fight against pandemics must be carried out at several levels
Despite all the reports of success about mask-wearing, the researchers in the current New York study make it clear: “In every pandemic or epidemic, mask-wearing is only one of several measures.” The most effective strategies involved “a multi-level response, including vaccination (when available), isolation of infectious people, and protection through risk reduction, including the use of high-quality masks.”
The Japanese are the ones who use masks the most
The Japanese seem to have better understood that masks help contain diseases. Because, as a study from Osaka University reveals, Japan has had the highest mask wearing rates in the world during the Covid pandemic. And even after the pandemic, the Japanese do not abandon their beloved masks. “Our online survey shows that 59 percent of Japanese participants still wear masks even after the downgrade of the legal status of COVID-19,” explains Michio Murakami, author of the study published in the International Journal of Disaster Risk Reduction. However, Murakami also writes that even before the pandemic, 67 percent of Japanese wore masks. 291 people between 20 and 69 years old participated in the survey in April and June 2023.
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Masks as a means to reduce fears
But what motivates Japanese people to wear masks, even without medical necessity? In his study, Murakami discovered that the Japanese also wear masks for socio-psychological reasons. “A common reason is what we call ‘relief.’ Wearing a mask reduces anxiety for many people,” explains Murakami. A second reason is the norm. “People wear the mask because they see others wearing a mask.”