Wearing face masks is an effective way to stop the spread of the coronavirus, a landmark study has found.
Researchers in the US have found a 10 per cent rise in self-reported mask wearing is associated with a three-fold increase in the odds of keeping the R number below 1.
R is the number of people that one infected person will pass on the virus to, on average. When the R value is less than 1, it means the epidemic is shrinking.
However, the scientists warn that while face coverings can help control Covid-19 transmission in the community, they should not be a replacement for other coronavirus measures such as social distancing.
The horizontal line in the coloured box represents the average R rate for the coronavirus when compared to how many respondents in an area said they were ‘very likely’ to wear a mask when visiting friends or family and attending the supermarket
Pictured, the percentage of individuals who say they are ‘very likely’ to wear a mask to the grocery store and with family or friends in the USA. The more yellow/green an area is, the more people in that region say they are ‘very likely’
The US-based experts said their findings, published in the journal Lancet Digital Health, suggest that communities with high reported mask-wearing as well as physical distancing are the most likely to be able to control transmission.
Ben Rader, of Boston Children’s Hospital and Boston University, co-author of the study, said: ‘An important finding of this research is that mask wearing is not a replacement for physical distancing.’
The researchers used a web-based survey to gather data on face-covering habits from more than 300,000 people across all 50 US states and Washington DC between June 3 and July 27 2020.
They compared this to anonymised data of smartphone users from Google showing movement patterns. This information was shared only after users had given consent.
Research found a ten per cent rise in the amount of people using coverings resulted in odds of R being below 1 more than tripling (stock)
Wear a mask in the office, school, and OUTDOORS, WHO says
People in areas where there is high transmission of Covid-19 should wear face masks indoors, including in offices and schools, according to new guidance from the World Health Organization (WHO).
Coverings should also be worn in private homes if someone comes inside who does not live there.
Other additions to the guidance include children over the age of 12 following the same advice as adults and wearing a mask outside if social distancing of one metre is not possible.
In the updated guidance sheet, the WHO admits there is ‘limited evidence’ the masks stop the transmission of coronavirus.
Recent studies have found conflicting evidence about masks, with a landmark piece of research finding they do not stop the wearer catching the virus.
Researchers say the study is observational and is therefore unable to prove a direct causal link between mask wearing and transmission.
The majority of people in the study said they are ‘very likely’ to wear a face mask to the supermarket (84.6 per cent) but less than half (40.2 per cent) wear one when visiting family.
Very few respondents reported they were ‘not likely to wear a mask at all’ (4.7 per cent).
Self-reported mask-wearing was highest among people aged 65 and over (48 per cent) and varied across the US, with the highest proportion of reported mask-wearing found along the coasts and southern border of the US, as well as in cities.
Researchers say it is possible the people who were quizzed as part of the study are also more likely to engage in other behaviours that reduce their risk of Covid-19 infection, such as increased hand washing, which was not addressed in the study.
Dr Christina Astley, a clinician and epidemiologist with Boston Children’s Hospital and Harvard Medical School, and study co-author, said: ‘Our findings suggest widespread use of face masks may help to control Sars-Cov-2 (the virus that causes Covid-19) transmission.
‘The world is facing a more transmissible coronavirus strain, hospitals are struggling with new cases and vaccination programmes are still being rolled out.
‘Interventions are needed now to lower the burden on our healthcare systems.
‘This research provides additional evidence that those interventions should include wearing face masks to protect ourselves and as well as physical distancing.’