"Wearing masks in the community probably makes little or no difference." Such was the verdict of a recent Cochrane review, a systematic assessment of all medical research on masks.
Specifically, Cochrane found, "Wearing masks in the community probably makes little or no difference to the outcome of influenza-like illness/COVID-19 like illness"-or "To the outcome of laboratory-confirmed influenza/SARS-CoV-2"-"Compared to not wearing masks." Moreover, "The use of a N95/P2 respirators compared to medical/surgical masks probably makes little or no difference for the outcome ... of laboratory-confirmed influenza infection." Each of these claims was made with "Moderate certainty," the second highest of four certainty classifications.
Tom Jefferson, the lead author of both studies, says that Cochrane delayed the release of the 2020 study; it "Held it up for 7 months." If not for that delay, the review would have appeared just a few weeks after the CDC profoundly reversed its masking guidance-from don't wear masks to do wear masks-on April 3, 2020, citing no meaningful new evidence on which to base that change.
The needle moved in the opposite direction: Cochrane now says that masks "Probably", as opposed to "May", make "Little or no difference to the outcome of influenza-like illness." And in 2023, Cochrane explicitly added "COVID-19" and "SARS-CoV-2" to the list of things that masks apparently don't prevent-and could even increase-the spread of.
Another asserts, "If you are putting on a mask, you are doing a great job of protecting yourself." A third opines, "At the end of the day, people will do what they want, and science is not going to move some people one way or the other." He then proclaims, "But a mask does give you a big bang for the buck, and not just for COVID-19." In Vox, Kelsey Piper complains that the Cochrane review includes studies involving other viruses at other times, rather than just studies focused on Covid during the pandemic.
Piper praises the highly problematic Bangladesh study as "Finding very solid evidence," while the Cochrane review is somewhat "Scientifically irresponsible" and really "Quite bad meta-analysis." Likewise, Lucky Tran, writing for the Guardian, criticizes the Cochrane review because it includes other viruses in addition to Covid and because it evaluates masks' effectiveness as they are actually worn, rather than trying to guess how effective masks might be if people wore them as diligently as public-health officials would like.
Tran calls the Cochrane review part of "The avalanche of misinformation" and proclaims, "Masks are magnificent." He adds that masks "Are a visible symbol that the pandemic is ongoing"-another apparent virtue.
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