Mask a must, finds largest study of its kind by Stanford Medicine and Yale researchers

Wearing masks reduces the chances of contracting Covid-19 up to 34 percent, and the government should act aggressively to force people to wear masks, says a recent study on 3.5 lakh people in rural Bangladesh.

Awareness campaigns can increase the use of masks up to three times, finds the study, considered the largest of its kind.

Titled "The Impact of Community Masking on COVID-19: A Cluster-Randomized Trial in Bangladesh", the study was conducted by researchers from Stanford Medicine School and Yale University between November 2020 and April 2021.

The randomised trial involving nearly 350,000 individuals in 600 villages also found that surgical masks are more effective than fabric ones in preventing transmission.

These findings come at a time when most people appear to be nonchalant about wearing masks and maintaining social distancing.

Also, the state of mass inoculation is quite poor. With a target of vaccinating 80 percent (13.51 crore) of the people of the country, the government started a campaign on February 7. So far, some four percent of the population have got both shots of a vaccine. If the campaign continues at its current pace, it may take around 10 years to reach the target of 80 percent coverage.

The study findings were released on September 1 on the website of Innovations for Poverty Action.

Local NGOs GreenVoice and Innovations for Poverty Action Bangladesh were partners in the study.

"Wearing masks properly reduces symptomatic infection rate by 34 percent among the most vulnerable group, aged 60 and above," Ahmed Mushfiq Mobarak, lead author of the study, told The Daily Star yesterday.

He added that this was the largest study of its kind anywhere in the world.

Bangladesh-born Mobarak, a professor of economics at Yale, said the study was conducted in two phases: in phase I, the researchers wanted to see how to make people aware of the benefits of wearing masks consistently and in phase II, they sought to see if the intervention reduced Covid-19 transmission.

The researchers distributed free surgical masks, informed people about the importance of face-coverings, reminded people to wear masks when they were found unmasked, and engaged community leaders to persuade people to wear masks continuously in the areas they intervened in and termed them "treatment areas".

Then there were "control areas" where the researchers did not intervene.

"We found that use of masks increased threefold in the treatment areas.  In control areas, the rate of mask-wearing was 13 percent while it rose to 42 percent in the treatment areas," he said.

The study also separately examined the rate of mask-wearing inside mosques, markets, and places like tea stalls, entrance to restaurants, and the main roads.

It found a slight increase in physical distancing in public spaces in treatment areas.

The findings included that wearing a surgical face mask covering the mouth and nose is an effective way to cut the occurrence of Covid-19 in community settings.

The intervention led to a 9.3 percent drop in symptomatic Covid and an 11.9 percent drop in the prevalence of Covid-like symptoms.

"We found clear evidence that surgical masks are effective in reducing symptomatic seroprevalence of SARS-CoV-2 [coronavirus], while cloth masks clearly reduce symptoms, we cannot reject they have zero or only a small impact on symptomatic SARS-CoV-2 infections," the summary reads.

Seroprevalence provides estimates of antibody levels against infectious diseases and is considered the gold standard for measuring population immunity due to past infection or vaccination.

"Surgical masks have higher filtration efficiency, are cheaper, are consistently worn, and are better supported by our evidence as tools to reduce Covid-19," the study summary continues.

Wearing of masks by local leaders, mask distribution, and other promotional activities increase mask-wearing and physical distancing among people, leading to lower illness, particularly in older adults, it added.

Co-author of the study Alamgir Kabir told The Daily Star that the researchers found stronger support for the use of surgical masks than fabric masks to prevent Covid-19.

"If we launched the mass awareness campaign in the rural areas engaging local administration, political parties and religious people, the severe surge of Covid-19 in Bangladesh could have been averted," he said.

Kabir, also senior operation manager of Innovations for Poverty Action Bangladesh, said making people aware through a mass campaign could contain the spread of Covid-19.

Abul Bashar Mohammed Khurshid Alam, director general of the Directorate General of Health Services, said, "We have repeatedly said there is no alternative to wearing masks. We launched mass awareness campaigns and such campaigns will be intensified. Everyone must wear a mask, even if they are vaccinated."