New evidence shows mask wearing reduces COVID-19 infections in the community.


A recent study examining strategies to increase mask wearing and the effect of mask wearing on the number of COVID-19 infections is a work of art.

Those Nerdy Girls are celebrating this study for two reasons: Excellent scientific rigor and real life implications.

The take home message from this great real-world study: Masks work in reducing COVID-19 cases in the community. Surgical masks performed best in reducing COVID-19 cases at the community level. Mask use tripled using the NORM model to increase mask uptake.

The study was conducted in Bangladesh in partnership with policymakers, researchers, and multiple other organizations. The study included 600 villages and 340,000 adults. Whole villages (and not individuals) were randomized to an intervention group or a control group. This method, called cluster randomization, allowed for the examination of community level outcomes for mask wearing, a practice that is very visible and affects both mask wearers and non-mask wearers. 100 villages received cloth masks and 200 villages received surgical masks. The remaining 300 villages were observed, though did not receive any intervention to increase mask wearing.

All villages in the intervention group received the following: No-cost mask distribution, Offered information about mask wearing, Reinforcement of mask wearing in-person and in public spaces, and Modeling of mask wearing by trusted community leaders.

Mask use increased from 13 out of 100 people to 42 out of 100 people on average in villages who received the mask wearing intervention, a 29% increase in mask wearing. Overall, symptomatic infections in villages who were in the intervention group decreased by 9%. Villages that received surgical masks had a 12% reduction in COVID-19. The use of surgical masks prevented 1 in 3 symptomatic COVID-19 infections among people over the age of 60 who are at highest risk for death and debility from the disease.

The implications of this study are HUGE! Increased community masking decreases COVID-19 disease in real-world settings. Higher rates of community masking, as you might see with mask mandates, are likely to produce even larger reductions in COVID-19 cases. Surgical masks performed better than cloth masks at reducing COVID-19 disease, though cloth masks are better than no masks. Those Nerdy Girls are grateful to the study team and participants for their excellent scientific contributions. We hope the results influence individual and community actions to mask up to control this painful and disruptive pandemic.

Additional Reading

Detailed summary of the article published by Innovations for Poverty Action

Tweetorial by @Jabaluck (Jason Abaluck, the lead author of the study)

Original Article

Link to Original FB Post