The benefit of mouth and nose protection against the spread of the coronavirus has long been the subject of heated debate. Almost at the same time as the mask requirement on buses and trains was abolished, an overview study by the renowned research network Cochrane is now causing explosives. Mask opponents see their arguments confirmed. But it’s not that easy.

Claim: The Cochrane study proves that masks offer little or no protection against infection with the coronavirus.

Evaluation: Such an interpretation of the work is wrong.

Facts: In the Cochrane paper, the authors bundle study results on the effectiveness of non-pharmacological measures – such as quarantine, washing hands and wearing a mask.

They examined a total of 78 studies, including works on the influenza virus, the Covid pathogen Sars-CoV-2 or the severe acute respiratory syndrome (Sars). The majority of the surveys relate to classic peak seasons for respiratory viruses up to 2016, not to the corona pandemic.

Based on the studies reviewed, the authors write that wearing masks in the population probably has little or no effect on the occurrence of diseases such as flu and corona. However, they limit the validity of the results. ‘The high risk of bias, the differences in how outcomes are measured and the relatively low level of compliance during the study periods make it difficult to draw firm conclusions,’ they point out.

How well masks actually protect against the corona virus urgently needs to be further investigated. The authors speak of “research gaps”.

In a statement, Cochrane Germany wants to prevent “far-reaching interpretations” in social media: It should be borne in mind that most of the studies examined interventions such as the provision of masks. Whether and to what extent these were then worn by the people is not certain.

“The Cochrane study is not very meaningful,” explains Eberhard Bodenschatz, Professor of Physics and Director at the Max Planck Institute for Dynamics and Self-Organization in Göttingen. A major problem with the study is that it brings together various respiratory diseases such as corona and normal flu.

“Our studies have clearly shown that masks are physically wonderful protection,” he told the German Press Agency. They improved protection against infection by a factor of at least ten to a hundred. The various individual studies are not comparable.

Bodenschatz also expresses criticism of the authors: “In one sentence they write that masks don’t work, and a paragraph later they admit that they can’t really say it.” This type of communication is unfortunate.

Various scientific analyzes have long shown that masks protect against infection with the corona virus. An overview study from mid-2020, published in the renowned journal “The Lancet”, shows that protective masks can significantly reduce the risk of infection.

A study published in the journal “PNAS” at the end of 2021, in which Bodenschatz was significantly involved, showed that masks can significantly reduce the risk of infection: If a non-infected person and an infected person wear well-fitting FFP2 masks, the maximum risk of infection is after 20 minutes accordingly, even at the shortest distance in a room hardly more than one per thousand.

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