The spread of Corona was slowed by masks

It has been and is the subject of heated debate: the question of whether or not masks can prevent the spread of the coronavirus. A team led by New York scientist Shama Cash-Goldwasser has published a new comprehensive study. The researchers analyzed several high-quality observational studies. The result: face masks can limit the spread of coronaviruses. “Available data support the use of masks in the population to reduce transmission of SARS-CoV-2,” the researchers write.

According to the study, these findings should serve as a basis for future management of epidemics and pandemics caused by respiratory viruses. “The effectiveness of the measures will depend at least in part on using lessons learned from the Covid-19 pandemic. High-quality masks made widely available could also play an important role in containing pathogens in future pandemics,” the researchers wrote.

The researchers analyzed several observational studies on the effects of masks on airplanes, in schools, and in household and community contacts. They say a Covid-19 outbreak on the aircraft carrier USS Theodore Roosevelt early in the pandemic, before crew members could develop immunity, was instructive. “More than 80% of those who said they did not wear a mask were infected,” the scientists write. “In contrast, those who said they were wearing a mask were 30% less likely to be infected.” Because people on board ships often live together for long periods of time in confined, poorly ventilated spaces, the risk of developing respiratory diseases is generally high.

However, scientists admit: even the best masks do not offer complete protection. Effectiveness depends on many factors. “The benefits of masking are limited if masks are not worn wherever transmission occurs.” For example, healthcare workers who consistently wear masks when working with patients could still become infected if the mask is removed, during breaks, or during conversations with colleagues. Additionally, both mask type and fit are crucial to effectiveness.

According to the study, laboratory studies have shown that masks can substantially 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 the transmission of coronaviruses.

The overall study “Masks during pandemics caused by respiratory pathogens: evidence and implications for action” analyzed several so-called individual observational studies. In these studies, the conditions are not influenced by the researchers. In return, randomized controlled trials (RCTs) work with an experimental group and a control group using placebos.

However, in their overview analysis, researchers led by Shama Cash-Goldwasser intentionally focused “only” on the observational studies published so far. “Randomized trials and meta-analyses may have significant limitations and should not be the sole or even primary basis for public health decisions,” the researchers wrote. “Such 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 focus on randomized trials. Unfortunately, these are “limited in number, scope, and statistical significance,” the researchers explain.

Only in June this year did the study “Physical interventions to interrupt or reduce the spread of respiratory viruses” conducted by the renowned Cochrane research network cause a stir. It states among other things: “The use of masks in the population probably has little or no influence on the onset of influenza-like or COVID-19-like illnesses compared to the non-use of masks.”

Opponents of masks have interpreted this statement to mean that masks do not protect against coronavirus infection. The Cochrane Research Network quickly 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 pointed out: “The risk of bias in RCTs and cluster RCTs was usually high or unclear.”

Despite all the successful reports of mask wearing, the researchers of the current New York study make clear: “In any pandemic or epidemic, wearing masks is only one of many measures.” The most effective strategies involved “a multi-tiered response, including vaccination (where available), isolation of infected individuals, and protection through risk reduction, including the use of high-quality masks.

The Japanese use more masks

The Japanese seem to have better understood that masks help contain diseases. Because, as a study by Osaka University finds, Japan had the highest mask use 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% of Japanese participants still wear masks even after the legal status of Covid-19 was downgraded,” 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% of Japanese wore a mask. In April and June 2023, 291 people aged between 20 and 69 participated in the survey.

Masks as a means to reduce fears

But what drives the Japanese to wear masks even without medical necessity? In his study, Murakami found that Japanese people 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 masks because they see others wearing masks.”