If you go back to when we introduced mask mandates first. I think it was back in June or July 2020. Cases were going up very, very rapidly, and then the mask mandate actually brought them under control, oh, within weeks, within a couple of weeks.”
During an interview on the BBC 5 Live Breakfast programme, Professor Trish Greenhalgh, a healthcare expert at Oxford University, said that mask mandates in the UK were introduced during a time of rapidly rising Covid-19 infections, which came under control a few weeks later.
There is evidence that masks do at least partly protect people from spreading and catching Covid, but this does not accurately describe what happened when mask mandates were introduced in the UK.
Full Fact contacted Professor Greenhalgh, who agreed that she had misremembered what happened in 2020. The mistake was also noted by at least one Twitter user.
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When were mask mandates introduced?
In England, masks began to be required on public transport on 15 June 2020, and in shops on 24 July 2020.
The Scottish Government began to recommend face coverings in April 2020, and they became mandatory in certain indoor settings in Northern Ireland in August 2020, and in shops in Wales in September 2020.
We have considered the evidence in England specifically, because it covers the period Professor Greenhalgh was talking about, and provides the best data on Covid infections at the time.
The Coronavirus Infection Survey from the Office for National Statistics shows that the number of Covid infections in England was generally flat and low in the summer of 2020, following the end of the first wave in the spring.
It does not seem right to say that infections were rising very rapidly, although there were very slight rises, within the margin of uncertainty, in the weeks when the mandates were introduced.
Nor was there a significant fall in the weeks following the introduction of the mandates, with infections remaining generally flat until September, when they began to rise at the beginning of the second wave.
This does not mean that the mask mandates had no effect. It is possible that the number of Covid infections might have risen earlier or faster, had the mandates not been introduced.
As we’ve written before, there is evidence that masks offer some protection against catching Covid.
While they are considered to protect the wearer (and some masks, such as respirators are thought to offer a fair bit of protection this way), a particularly important part of the way that facemasks and coverings can reduce the spread of Covid-19 is through ‘source control’.
This is where a facemask or covering reduces the number of particles released into the surrounding air by an infected wearer. In this capacity, wearing a facemask offers protection to others as well.
Professor Greenhalgh also shared some studies with us, which suggest that mask mandates specifically may be associated with a lower incidence of Covid-19.
After this article was originally published, a BBC spokesperson replied to us saying: “Presenters strive to uphold the highest journalistic and editorial standards when interviewing guests and experts. We are satisfied that all claims were adequately challenged by our presenter.”
Image courtesy of Kobby Mendez