Yale study on Bangladesh shows usefulness of masks

A study based on a randomised research project in Bangladesh has shown that widespread wearing of surgical masks can limit the spread of the coronavirus in communities.

The study, by far the largest randomised study on the effectiveness of masks at limiting the spread of coronavirus infections, tracked more than 3,40,000 adults across 600 villages in rural Bangladesh, reported The Washington Post on Thursday.

The study was led by principal investigators Abaluck, Laura Kwong, Steve Luby, Ahmed Mushfiq Mobarak and Ashley Styczynski — a globe-spanning team that includes researchers from Yale, Stanford and the Bangladeshi nonprofit GreenVoice.

The team chose Bangladesh because co-author and Yale economist Mobarak was from the country and had worked there before, and because of increased options for funding.

The sheer scale of the project, which began in November and concluded in April 2021, is notable. About 178,000 Bangladeshi villagers were in an intervention group and encouraged to use masks. An additional 163,000 were in a control group, where no interventions were made.

The project assessed the levels of mask-wearing and physical distancing through direct observations from plain-clothed staff in the community at mosques, markets and other gathering places.

The study was separated into two parts. First, researchers found that four interventions increased mask-wearing.

The four interventions included no-cost free masks distribution, offering information on mask-wearing, reinforcement in-person and in public, and modeling and endorsement by trusted leaders.

Utilizing those four interventions, researchers found mask-wearing increased to 42 per cent in targeted villages, up from 13 per cent in control villages.

In the second part of the study, researchers checked those in the targeted and control villages for Covid-19 symptoms.

If symptoms were reported, they were tested for Covid-19. Researchers said in villages that were targeted with mask promotion programs, there were 9.3 per cent fewer symptomatic infections than in the control villages.

If surgical masks were distributed, instead of cloth masks, infections were 11 per cent lower overall, 23 per cent lower among those 50-60, and 35 per cent among people over 60.

The researchers said the results of the study showed, “there is clear evidence that community mask-wearing can reduce Covid-19” and “the effects were substantially larger in communities where surgical masks were distributed.”

Further, the researchers said mask-wearing can be “increased through a combination of four core intervention elements, now called the ‘NORM’ model.”

The NORM model stands for “No-cost mask distribution, offering information, reinforcement to wear masks, and Modeling by local leaders.”

Researchers said while this method helped increase mask-wearing, other ideas like village-level incentives, text messages, or even “altruistic messaging” didn’t help increase usage of masks.

According to the researchers, the study opens the door to future research that should analyze expanding mask usage to fight other diseases.

“Whether people with respiratory symptoms should generally wear masks to prevent respiratory virus transmission –– including for viruses other than SARS Co-V-2 –– is an important area for future research,” researchers reported in the study. “The findings from this study suggest that such a policy may benefit public health.”

The study is under peer review with the journal Science. The authors granted journalists an early look at the results because of their potential importance in global public health debates.

Independent experts that were asked to look at the research praised its scale; some suggested that it might be the most convincing argument yet for mask-wearing.

The authors plan to conduct more research, including an evaluation of how masks limited symptomatic spread — whether by decreasing the viral load so fewer people experience symptoms, or by preventing infections entirely.