Skip to content
The methodOpen data
Back to the collection

Impact of community masking on COVID-19: A cluster-randomized trial in Bangladesh

Jason Abaluck, Laura H. Kwong, Ashley Styczynski

Show all 22 authors

Ashraful Haque, Md. Alamgir Kabir, Ellen Bates-Jefferys, Emily Crawford, Jade Benjamin-Chung, Shabib Raihan, Shadman Rahman, Salim Benhachmi, Neeti Zaman Bintee, Peter J. Winch, Maqsud Hossain, Hasan Mahmud Reza, Abdullah All Jaber, Shawkee Gulshan Momen, Aura Rahman, Faika Laz Banti, Tahrima Saiha Huq, Stephen P. Luby, Ahmed Mushfiq Mobarak

2022 · Science

Economics
Read the paper
HN score
1.5
Mentions
7
Readers
6
Months
4
What’s in a score?

From the abstract

Persuading people to mask Even in places where it is obligatory, people tend to optimistically overstate their compliance for mask wearing. How then can we persuade more of the population at large to act for the greater good? Abaluck et al . undertook a large, cluster-randomized trial in Bangladesh involving hundreds of thousands of people (although mostly men) over a 2-month period. Colored masks of various construction were handed out free of charge, accompanied by a range of mask-wearing promotional activities inspired by marketing research. Using a grassroots network of volunteers to help conduct the study and gather data, the authors discovered that mask wearing averaged 13.3% in villages where no interventions took place but increased to 42.3% in villages where in-person interventions were introduced. Villages where in-person reinforcement of mask wearing occurred also showed a reduction in reporting COVID-like illness, particularly in high-risk individuals. —CA

Metadata: Crossref. Abstracts retain their original authors’ rights.

In the conversation

Original HN comments, with labels from simple text rules. A label describes the whole comment and may miss context or irony. Read the discussion to make up your own mind. About the labels

7 selected excerpts · 7 total mentions

rallison
Strong recommendation · rule
One of the best-known mask studies is the Bangladesh mask study, which is as close as exists for a masking efficacy RCT. https://www.science.org/doi/10.1126/science.abi9069 First, note that this wasn't studying in the context of a mask mandate - in the sample villages, masks were distributed, and people were recommended to wear masks when around others. In practice, this brought mask usage up to 42% on average, as compared to 13% in control villages. So, even in this context where the majority of people weren't wearing masks, they still saw an effect in the cloth mask villages. They also saw a larger effect in the surgical mask villages. Thread from one of the study…
Read the full comment
authors: https://twitter.com/Jabaluck/status/1433036923610742789 It is worth noting that the effect was smaller and the sample size for cloth mask villages smaller than for surgical mask villages, so the confidence is lower than for surgical masks. But with that said, note this from the study author: > We find a clear and large statistically significant impact on COVID symptoms. We find an imprecise zero for serologically confirmed COVID. The most likely interpretation is that cloth masks reduce COVID, but not as much as surgical masks. https://twitter.com/Jabaluck/status/1433227618497728514 Now, was the effect relatively small for cloth masks? Yes. But given the results here, plus results we have from mechanistic studies of cloth masks, a reasonable conclusion is something along the lines of: cloth masks have some effect on transmission, albeit a relatively small effect. Other types of masks are better. Additionally, if the assumption of "the types of masks worn by the vast majority of school children" is correct, then studies showing that mask mandates in schools had an effect on transmission would suggest some efficacy for cloth masks. Two relatively large-scale observational studies: https://twitter.com/roby_bhatt/status/1502244997764157442 That said, I'm endlessly disappointed that there wasn't a consistent, strong push for people to upgrade from cloth to surgical once supplies of surgical masks were no longer an issue. And mask sizing was also an issue - there are so many masks out there that are oversized for kids. Imagine if the federal government had coordinated with schools across the country to ensure supplies of kid sized surgical masks at every school. Alas.
Original comment U.S. public health agencies aren't ‘following the science,’ officials say
felixgallo
Neutral mention · rule
literally quoting from that meta-analysis, which does not include many clinical trials that have demonstrated an impact: "Key messages We are uncertain whether wearing masks or N95/P2 respirators helps to slow the spread of respiratory viruses based on the studies we assessed." Example very large study published in a reputable journal: https://www.science.org/doi/10.1126/science.abi9069?cookieSe...
Original comment Stories removed from the Hacker News Front Page, updated in real time
SnowProblem
Neutral mention · rule
It's far from perfect, but I believe this to be the best RCT we have on masks out of Bangladesh: https://www.science.org/doi/10.1126/science.abi9069 We found clear evidence that surgical masks are effective in reducing symptomatic seroprevalence of SARS-CoV-2. Although cloth masks clearly reduce symptoms, we find less clear evidence of their impact on symptomatic SARS-CoV-2 infections, with the statistical significance depending on whether we impute missing values for nonconsenting adults. I don't believe we have any good studies out of the US or Europe. There's a discussion about this and more on the Econ Talk podcast this week: https://www.econtalk.org/vinay-prasad-on-the-pandemic/
Original comment Polio Detected in US
epups
Neutral mention · rule
A lot of the evidence cited here is of very low quality/interest, such as observational and correlational studies. It does cite the best study we have so far, a large-scale RCT from Bangladesh: > A report in Nature explained that researchers running a randomized controlled trial (RCT) of community mask use in Bangladesh “began by developing a strategy to promote mask wearing, with measures such as reminders from health workers in public places. This ultimately tripled mask usage, from only 13% in control villages to 42% in villages where it was encouraged”, and “then compared numbers of COVID-19 cases in control villages and the treatment communities”. They found that the…
Read the full comment
number of infections in mask wearing communities decreased, with a reduction of COVID symptoms using surgical masks to 0.87 times the incidence in unmasked communities, and 0.91 times when using cloth masks. Unfortunately they have misquoted the numbers here. Surgical masks reduced the prevalence of COVID-like symptoms by 11%, and of actual confirmed COVID cases by 9.5%, while cloth masks did about half as well [0]. So tripling the number of people wearing masks up to about 40% of the population has a very mild effect on COVID spread, and this is before Omicron. I don't think this makes a good case for mask mandates in 2022. [0] https://www.science.org/doi/10.1126/science.abi9069
Original comment Masks for Covid: Updating the Evidence

Keep following the thread.

More in Economics

More from the same topics.

2010arXiv

Markets are efficient if and only if P = NP

Philip Maymin

I prove that if markets are weak-form efficient, meaning current prices fully reflect all information available in past prices, then P = NP, meaning every computational problem whose solution can be verified in polynomial time can also be solved in polynomial time.

EconomicsAlgorithms
23 mentions22 months
1HN score