Researchers shoot holes in study touted for confirming 'masks work' in curbing COVID

An acclaimed study on the effectiveness of masks in reducing symptomatic COVID-19 is facing new scrutiny after a researcher highlighted the minuscule infection differences between "treatment" and control groups randomized across 600 Bangladeshi villages.

Accused of design flaws and overstating its findings when it was released in late August, the study's newly released data show only 20 more symptomatic COVID cases in the villages that didn't receive masks and related education, reminders and "role modeling by community leaders."

In a total study population of 342,126 adults, 1,106 people in the control group tested positive, compared to 1,086 in the treatment group. The latter group represented 52% of the study population.

"I have a hard time going from these numbers to the assured conclusions that 'masks work' that was promulgated by the media or the authors after this preprint [not yet peer reviewed] appeared," University of California Berkeley professor Ben Recht, who studies machine learning, wrote in an essay last week.