BMJ vs Cochrane: Who is rewriting the science on face masks?
A bold ‘state of the art’ review in the BMJ aimed to settle the science on face masks. But does it hold up to scrutiny?
The debate over face masks hasn’t faded—it has calcified.
Five years after the onset of Covid-19, the question of whether masks are an effective public health tool continues to divide experts and polarise the public.
At the heart of this divide is a clash between competing standards of evidence.
Earlier this year, the BMJ published a sweeping “state of the art” review led by Professor C. Raina MacIntyre.
The paper argued that data collected during the pandemic confirmed the effectiveness of masks—particularly high-grade respirators like N95s—in both healthcare and community settings.
“Extensive evidence generated during the Covid-19 pandemic confirms the superiority of respirators,” the authors wrote, adding that even cloth masks “provide some protection” during periods of high transmission.
The review concluded there is “ample evidence on the effectiveness of masks and respirators… to inform consistent policy.”
But that conclusion puts the BMJ review on a collision course with a far more rigorous evaluation - the 2023 Cochrane review - which applied the highest level of scientific rigour to the same question.