Study questions the use of masks against Covid-19 and causes controversy

A systematic review by British epidemiologists concluded that the use of masks may not work for the control of respiratory infections such as the flu, severe acute respiratory syndrome and also Covid-19.

The study called “Physical Interventions to Stop or Reduce the Spread of Respiratory Viruses” analyzed the results of 78 surveys done in various parts of the world, before and during the pandemic, to determine the actual effectiveness of mask wearing and hand hygiene to stop the transmission of these diseases.

The main conclusion caused great surprise and controversy: “we are not sure whether wearing masks or N95/P2 respirators helps to slow the spread of respiratory viruses”, said the epidemiologists.

According to them, “mask wearing may make little or no difference in how many people have contracted a flu-like illness or Covid-19; and it probably makes little or no difference in how many people have the flu or Covid-19 confirmed by a lab test.”

The work was carried out by 12 epidemiologists, led by British professor Tom Jefferson, and published by the non-profit organization Cochrane – an entity highly respected for its studies related to public health.

Scientists have said that even N95 surgical masks do not work well enough to stop the virus from spreading.

“Compared to using medical or surgical masks, using N95/P2 respirators likely makes little or no difference in how many people have confirmed flu; and may make little or no difference in how many people get a flu-like illness or respiratory illness,” the study says.

Hand hygiene, on the other hand, had a proven effect to prevent the spread of viruses. “Following a hand hygiene program may reduce the number of people who contract a respiratory or flu-like illness, or have confirmed flu, compared with people who do not follow such a program,” the epidemiologists said.

The work contradicts one of the most important recommendations made by the World Health Organization during the pandemic, which was precisely the systematic use of respiratory masks to prevent the spread of the new coronavirus. The recommendation is still in effect.

A CNN Brasil spoke with Fiocruz infectologist and professor at the Federal University of Mato Grosso do Sul Julio Croda, who stated that “the Cochrane review, despite the correct methodology, is not the best way to answer whether masks work as a public health measure ”.

Croda states that the authors of the study themselves “make it clear that in most of the clinical trials analyzed there was not an adequate design, with follow-up failure and lack of important information such as the quality of the masks, time of use, adherence and correct use in adults and children”.

He also recalled that “evidence of efficacy at the population level is not the same as evidence in individuals or in laboratories” and that “individual clinical trials are not a good method to evaluate population interventions”.

Controversy A good part of the controversy was created by an article by the American journalist Bret Stephens published in The New York Times. The journalist, a conservative who has questioned climate change in the past but changed his mind after a trip to Greenland, said the study would prove that masks simply do not help in the attempt to stop Covid-19.

“Those skeptics who were angrily ridiculed as cranks and occasionally censured as ‘disinformers’ (for being against masks) were right. The leading experts who supported (the masks) were wrong. In a better world, it would be up to this latter group to recognize their mistake, along with its considerable physical, psychological, pedagogical, and political costs,” wrote Stephens.

The paper has been heavily criticized on the internet by people who think it overreacted and who believe the study is not definitive.