Wearing face masks does NOT stop the spread of Covid-19 and TRIPLES the chance to keep the coronavirus R rate below 1, the study shows
- U.S. researchers gave a questionnaire to more than 300,000 people in 50 states
- The 10% increase in masks makes R 3 times less likely to be less than 1
- Experts add that wearing a mask does not mean that social distancing is not necessary
Wearing face masks is an effective way to stop the spread of coronavirus, a reference study found.
Researchers in the US have found that a 10% increase in self-reported mask wear is associated with a threefold increase in the chances of keeping the R number below 1.
R is the number of people to whom an infected person will transmit the virus, on average. When the R value is less than 1, it means that the epidemic is shrinking.
However, scientists warn that while face coatings may help control the transmission of Covid-19 in the community, they should not be a substitute for other coronavirus measures, such as social distancing.

The horizontal line in the colored box represents the average R rate of coronavirus compared to the number of respondents in an area who said they were “very likely” to wear a mask when visiting friends or family and attending the supermarket.

This map shows the percentage of each geographic region in the U.S. that shows the percentage of people who say they are “very likely” or “somewhat likely” to wear a mask when visiting family or friends.
US experts say their findings, published in the journal Lancet Digital Health, suggest that communities with high-mask clothing as well as physical distance are the most likely to control transmission.
They used a computer model to determine what interventions are needed to reduce the R rate below 1, which is necessary for the pandemic to be considered “under control”.
Scientists have found that the chances of this happening increase 3.53 times if there is a ten percent increase in the population’s clothing, regardless of the basic level.
Ben Rader, of Boston Children’s Hospital and Boston University, co-author of the study, said: “An important finding of this research is that wearing a mask does not replace physical distance.”
The researchers used an online survey to gather data on face-covering habits from more than 300,000 people in all 50 US states and Washington DC between June 3 and July 27, 2020.
They compared this to the anonymized data of smartphone users at Google, which show motion patterns. This information was shared only after the users gave their consent.

In the picture, the percentage of people who say they are “very likely” to wear a mask at the grocery store and with family or friends in the US. The more yellow / green an area is, the more people in that region say they are “very likely.”

Research has shown that a ten percent increase in the number of people using coatings has led to a chance of R less than 1 than tripling (stock)
The researchers say the study is observational and therefore cannot prove a direct causal link between wearing a mask and transmitting.
Most people in the study said that they are “very likely” to wear a face mask at the supermarket (84.6%), but less than half (40.2%) wear one when visiting family.
Very few respondents reported that “they are unlikely to wear a mask at all” (4.7%).
Wearing a self-reported mask was highest among people aged 65 and over (48%) and varied across the United States, with the highest proportion of reported mask wearing being found along the coasts, and the southern border of the US, as well as in cities.
Researchers say that people who were interviewed as part of the study may also be more likely to engage in other behaviors that reduce their risk of Covid-19 infection, such as increased hand washing, which does not was addressed in the study.
Dr. Christina Astley, a clinician and epidemiologist at Boston Children’s Hospital and Harvard Medical School, and co-author of the study, said: “Our findings suggest that widespread use of face masks may help control Sars-Cov-2 (the virus that causes 19) transmission.
“People are facing a more transmissible strain of coronavirus, hospitals are battling new cases and vaccination programs are still ongoing.
“Interventions are needed now to reduce the burden on our health systems.
This research provides additional evidence that these interventions should include wearing masks to protect us and our physical distance.