Preliminary Study of 340,000 People Compares Groups, Encourages Use, and Proves Masks Effective Against Covid | Coronavirus

A study by researchers at the American universities of Stanford and Yale, which involved hundreds of thousands of people, confirmed that face masks are effective against Covid-19. And it also pointed out that groups that used masks with greater filtering power had better results in reducing cases of the disease. (Below, in three topics, understand the details of the study)

The results consider the observation, in real life, of the evolution of the pandemic among 340,000 residents of Bangladesh, Asia, who were analyzed considering two groups: those who used the protection (and were encouraged to expand its use) and those who did not. adopted in the period.

THE research has not yet been peer-reviewed or published in a scientific journal., but its preliminary version released by the organization “Innovations for Poverty Action” (IPA) has been identified among experts as the largest survey on the impact of a policy of wearing masks against Sars-Cov-2.

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The new scientific evidence that masks are effective is considered timely by experts in both the US and Brazil. In the United States, where the delta variant keeps the curve of cases and hospitalizations high, there is resistance to the use of masks. State governments even banned the use of protection in the classroom, which led to an increase in the number of cases in the last two weeks, with the return to face-to-face activities.

In Brazil, President Jair Bolsonaro wants to release the use of masks and, recently, Deputy Attorney Lindôra Araújo, of the Attorney General’s Office, claimed that it is “not possible to carry out rigorous tests that prove the exact measure of the effectiveness of the protective mask as means of preventing the spread of the new coronavirus”. The Health Minister himself, Marcelo Queiroga, said that he is against the obligation of wearing a mask by law and, also, against an alleged “fine industry”.

Distribution of masks in Bangadlesh — Photo: IPA/Disclosure

See below the main points of the study:

Why is the study different from others?

Previous studies have proven that masks are effective in reducing the spread of the virus.

This time, however, the researchers measured it in Large scale, directly in communities: 342,126 people from 600 villages in rural Bangladesh participated in the survey.

Before, research that measured the effectiveness of masks did so in the laboratory or with fewer volunteers (hundreds of people).

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The studies were conducted between November 2020 and April this year. Participants were analyzed in two groups. In the first, researchers randomly selected 300 villages with 178,288 people who were targeted with four different types of interventions to encourage mask use: free mask distribution, provision of correct information about use, public campaigns and encouragement through the example of leaders religious and reference persons in the community.

In the so-called control group, which had 163,838 people monitored, no incentive action was taken. As described in the survey, scientists have intervened so in some communities, but the opposite has not been done. In other words, there was no disincentive to the use of masks.

“We did not limit access to the control group’s masks for research. Even while data collection was being completed, we personally guaranteed donations of more than 100 million masks to distribute free in Bangladesh because the research had shown positive effects.” , explained Ahmed Mushfiq Mobarak, co-author of the study and professor of economics at Yale University.

Mobarak also highlighted that the research protocol was intensely discussed with entities such as the World Health Organization, the World Bank and the Bill and Melinda Gates Foundation, in addition to the Bangadlesh government itself.

How were the effects measured and what were the results?

Throughout the research, a portion of people who had symptoms of Covid-19 agreed to perform serological tests (to detect antibodies) to attest or rule out the contamination by the new coronavirus.

Overall, the group that was encouraged to wear masks had a 9.3% reduction in the prevalence of people infected with the new coronavirus compared to the group that was not encouraged to wear masks. In communities that exclusively used surgical masks, the reduction in prevalence was greater: 11.2%.

In other words, the study reinforced laboratory data and research with smaller groups that have already proven that masks with three layers are more effective than cloth masks.

In addition, at the end of the intervention, the group that was encouraged to wear masks had an increase of 29 percentage points in adopting the item. Before, the use was adopted by 13% of the population, a number that rose to 42% after the incentive measures. Even with the campaigns, researchers were still far from achieving full adherence to the use of masks among the population.

What does the percentage of case reduction mean?

According to scientists, caution is needed when interpreting the results. “Our results should not be taken as implying that masks can only prevent 10% of Covid-19 cases,” reinforce the authors in the text.

Epidemiologist Denise Garrett, vice president of the Sabin Institute for Vaccines, did not participate in the study, but analyzed the overall survey data. She points out that the percentage of cases reduction is significant.

It’s not a low percentage because this reduction was achieved with a modest increase in mask use. Also, considering that the transmission is exponential, the prevention of 10% of cases translates into important future reductions in the growth of the number of cases.“explains Denise Garrett.

“If a modest increase in mask use led to these reductions, universal use of masks can lead to much greater reductions.. Scientifically proven and proven!” commented Garrett.

Are masks important even if we already have vaccines?

Vaccines, although effective in preventing serious cases and hospitalizations for Covid, do not prevent transmission of the virus. In addition, the authors warn that the use of facial protection is a cheap and viable strategy for countries that do not yet have vaccines available to the entire population in an attempt to reduce the impact of the new coronavirus.

“Why do we talk about masks when vaccines are available? Vaccines are available to you, but not to rural Bangladesh (…) masks remain an important line of defense to limit the spread of Covid,” Mobarak said.

What we should know about PFF2/N95 masks

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