The debate about wearing masks accompanies the pandemic almost like the corona virus itself. People have been arguing about it since the beginning. A new study sparks the discussion once again – and initially seems to agree with the mask opponents. But it is not that simple. A fact check.

How much mouth and nose protection helps against the spread of the corona virus has long been the subject of heated debates. 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 providing explosives. The study is supposed to prove that masks are of little or no use in the fight against Corona.

The AfD sees its line confirmed, but the media also write of the “hardest blow” against Health Minister Karl Lauterbach (Welt) and “another gossip for German corona policy” (Cicero). So what’s behind it? A fact check.

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).

Important: The researchers examined a total of 78 studies, but only 18 studies on masks. And even more important: Only two of them were carried out during the Corona pandemic.

Only two mask studies during the corona pandemic:

5000 participants, April and May 2020. Half wore a mask, the other half didn’t. The result: The result is statistically ambiguous. Mask wearers were slightly better protected, but not significantly.

180,000 participants, November 2020 to April 2021. Free masks were distributed in some communities in Bangladesh and people were encouraged to wear them. In fact, significantly more people wore masks in the villages and there were fewer reports of people with corona symptoms. The authors of the study spoke of an overall reduction of twelve percent, and in the over-60s even 35 percent.

So speaks (rather) for wearing a mask during the pandemic. However, there are only two studies out of a total of 18.

Based on all the studies reviewed, the study 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 meaningfulness of the results: How well masks actually protect against the corona virus urgently needs to be further investigated. The authors speak of “research gaps”.

Experts like the virologist Alexander Kekulé consider the result “not surprising” – after all, most of the work relates to the time before the pandemic. Influenza is also “thrown together” with Corona. But: “These are different infection modes, a different infection pressure,” he says in Thursday’s MDR podcast. After all, there are significantly more infections in a pandemic. For comparison: “If we want to determine the effectiveness of umbrellas and do the study in Egypt, then you just don’t get a very clear effect that it’s of any use.”

The virologist draws a clear conclusion: “I am a virologist and in many situations we also protect ourselves from other viruses with the mask. It is absolutely clear that the masks have achieved something. There are also many studies for the corona pandemic that have proven this.”

“The Cochrane study is not very meaningful,” agrees 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,” says Bodenschatz of 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.

The expert also criticizes the authors: “In one sentence they write that masks don’t work, and a paragraph later they admit that they can’t actually 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, which was published in the renowned journal “The Lancet”, shows that protective masks can significantly reduce the risk of infection.

A study published in the specialist 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.