Scientists have concluded that surgical masks can reduce the spread SARS-CoV-2.
The highest-quality, gold standard type of clinical trial known as a random controlled trial, should result in "ending any scientific debate about whether masks are effective at fighting the spread of COVID-19," Jason Abaluck, Yale economist and one of the lead authors of the study, said to The Washington Post.
Megan Ranney, an emergency physician and Brown University professor, said to the Post that "this is an incredibly difficult but important study to conduct." "Anti-mask activists keep saying, "Where's the random controlled trial?" Here you go.
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Scientists have known for the past year that masks help to reduce the spread of the virus. It's difficult to determine how masks reduce transmission in real life, as not everyone masks, uses the same mask quality, or wears masks correctly.
Many other factors can complicate observational studies that compare mask-wearing behaviors with infection rates in different regions. Randomized trials, in which individuals are randomly assigned to receive medical intervention or not, are the strongest form of evidence. These trials are costly and time-consuming, especially if the behavior is masking.
Researchers from the U.S. and Bangladesh tested the effectiveness and use of masks in 600 villages across Bangladesh. According to the Post, the study involved more than 342,000 adults and is the largest randomized trial on mask usage.
According to the Post, the study was posted on Sept. 1 as a preprint to Innovations for Poverty Action's nonprofit website. It is currently being peer-reviewed for publication by Science.
The trial lasted from November 2020 through April 2021. About 178,000 people were given the intervention and 164,000 did not. According to the study, everyone in the intervention group was given free masks and had ample information about the importance of wearing masks. They also received reminders in person for eight weeks.
The intervention was not given to the people in the control group. Researchers placed observers in the community to monitor how many people wore masks properly and how far they walked away from mosques, markets, and main roads leading to villages and tea stalls.
The researchers conducted a survey of the participants to determine if they had COVID-19-like symptoms between five and nine weeks after the trial began. They then took blood samples from participants who were experiencing symptoms, and tested them for SARS-2 antibodies, approximately 10-12 weeks after the trial began.
Proper mask use tripled in the treatment group, going from 13.3% in the observation group to 42.3% with the masking intervention. The researchers also discovered that physical distancing was only 24.1% in the observation group, compared to 29.2% in treatment. The researchers noted that mask wear decreased in the intervention group over the five months following the trial. However, it remained 10% higher than the control group.
7.62% of COVID-19-like symptoms were seen in the intervention group, as opposed to 8.62% for the control group. Researchers collected blood samples from almost 11,000 participants and found that intervention decreased symptoms of COVID-19 infection by 9.3%.
The paper's authors stated that they should not take our results to mean that masks could prevent COVID-19 deaths or even 10% of COVID-19-related cases. This is because only 29 people were able to wear masks out of 100. They wrote that the total impact of near-universal masking may be possible with other strategies or stricter enforcement.
Villages received either surgical or cloth masks. The incidence of symptomatic infections in villages that received surgical masks was 11.2% lower than the control group. This percentage was even higher for older adults. Those who were 60 years old or older were provided with free surgical masks and other interventions. Symptomatic infection was reduced 34.7% in comparison to the control group. The researchers did not find that cloth masks had a reduced incidence of symptomatic infections compared to the control group.
Although the study is among many that demonstrate the benefits of masking it, it does have some limitations.
Researchers who asked participants to keep their identities private and to wear plain clothes may have noticed that they were wearing masks. The researchers were also able to survey them on how they physically distanced themselves from others. This may have led to the authors writing that the participants may have changed their behavior. Researchers couldn't determine if masks made symptoms worse by reducing viral load or if they caused new infections to be reduced completely.
Original publication on Live Science
