The Cochrane Review’s editor-in-chief on March 10 issued an unusual statement claiming that a recent paper published by the review does not show masks don’t work.
That interpretation of the paper is “inaccurate and misleading,” Karla Soares-Weiser, the editor-in-chief, said in a statement.
The January review found that, based on the current evidence, masks were not effective in reducing the spread of respiratory viruses.
Pooled results from the randomized, controlled trials analyzed for the review “did not show a clear reduction in respiratory viral infection with the use of medical/surgical masks,” the authors said, though several factors, including a high risk of bias in the trials, “hampers drawing firm conclusions,” they added.
“It would be accurate to say that the review examined whether interventions to promote mask wearing help to slow the spread of respiratory viruses, and that the results were inconclusive,” Soares-Weiser said on Friday. “Given the limitations in the primary evidence, the review is not able to address the question of whether mask-wearing itself reduces people’s risk of contracting or spreading respiratory viruses.”
The review’s corresponding author and several co-authors did not respond to requests for comment.
Soares-Weiser first commented to a New York Times opinion writer, Zeynep Tufekci. The writer was among those in 2021 who claimed that “the preponderance of evidence indicates that mask wearing reduces transmissibility.” Tufekci has also written on Twitter about wearing masks: “Why on earth not? What’s the upside of normalizing being a jerk?”
Despite mask mandates being introduced across the world after the COVID pandemic started, few randomized, controlled trials have been conducted to assess the efficacy of masks against COVID-19.
The few trials that have been conducted have returned mixed or negative results.
A study carried out in Bangladesh, promoted as supporting mask-wearing, was found in a reanalysis to suffer from significant issues, complicating its conclusions. Danish researchers in a different trial found no statistically significant difference in infections between those who donned masks and those who did not. And a trial in Guinea-Bissau did not establish that mask-wearing protected against COVID-19.
Some of the Cochrane authors have said that there is no evidence masks work.
“There is just no evidence that they make any difference. Full stop,” Dr. Tom Jefferson of the University of Oxford told independent journalist Maryanne Demasi.
“That statement is not an accurate representation of what the review found,” Soares-Weiser told The New York Times.
While the authors were clear on the limitations of the review in their abstract, a summary said: “We are uncertain whether wearing masks or N95/P2 respirators helps to slow the spread of respiratory viruses based on the studies we assessed.”
“This wording was open to misinterpretation, for which we apologize,” the Cochrane editor-in-chief said.
“While scientific evidence is never immune to misinterpretation, we take responsibility for not making the wording clearer from the outset. We are engaging with the review authors with the aim of updating the Plain Language Summary and abstract to make clear that the review looked at whether interventions to promote mask wearing help to slow the spread of respiratory viruses,” she added.
In November 2020, after Cochrane reviewed masks and other possible mitigation measures, Soares-Weiser acknowledged that “none [of the reviews] has found robust, high‐quality evidence for any behavioural measure or policy.”
“For each measure, though, lack of evidence of effectiveness is not evidence that the interventions are ineffective. Rather, the details of these reviews show why there may never be strong evidence regarding the effectiveness of individual behavioural measures when deployed, often in combination, in a general population living in the complex, diverse circumstances of individuals’ everyday lives,” she wrote. “Waiting for strong evidence is a recipe for paralysis. Public health officials must, instead, take measured gambles, based on circumstantial evidence from the reviewed studies and other sources.”