While the UK Health Security Agency (UKHSA) has advised adults who are displaying symptoms of flu or COVID to wear a face covering,<\/a> some public figures have advised all healthy adults to wear a mask in certain settings. For instance, in a briefing on 9 January, Scottish First Minister Nicola Sturgeon stated: \u201cWe continue to advise those over the age of 12 should wear face coverings when on public transport or in public indoor spaces.\u201d<\/p>\n However, as COVID begins to stabilise in the UK, some scientists have questioned how effective face masks are at controlling current case numbers.<\/p>\n \u201cMasks were really helpful early in the pandemic. And for people to argue that masks weren\u2019t is seriously wrong,\u201d Prof Paul Hunter<\/a> from the Norwich Medical School of the University of East Anglia tells BBC Science Focus.<\/em><\/p>\n \u201cBut there is evidence that masks were an essential part of our control measures up until the point that we\u2019d effectively vaccinated as many people as we were going to. What we\u2019ve seen this year is that their protection has evaporated.\u201d<\/p>\n Where\u2019s the evidence for this? Primarily, the claim hinges on data collected by the Office of National Statistics (ONS) between November 2021 and May 2022 that monitored how likely people who did and didn\u2019t wear a face mask would test positive for COVID<\/a>.<\/p>\n These figures indicate that throughout the end of 2021, children and adults who declared they \u201calways\u201d wore a face covering at work or school were less likely to test positive for COVID-19 compared to those who \u201cnever\u201d or \u201csometimes\u201d wore a mask. As you may expect. However, from January to May 2022, this trend faded. The likelihood that somebody who never or sometimes wore a mask would test positive was extremely similar to the chance a person who always wears a face mask would test positive.<\/p>\n In other words, from January to May 2022, the risk of getting a COVID infection was nearly the same for those who did and didn\u2019t wear a mask. And it\u2019s from these data that scientists like Hunter have suggested factors other than face masks, like the population\u2019s immunity levels, play a bigger role in determining levels of COVID in the population.<\/p>\n No, scientists aren\u2019t all in agreement. Some have said there isn\u2019t enough data, highlighting how the ONS figures on mask-wearing were last collected in May 2022 \u2013 eight months ago.<\/p>\n This means, they say, the study can\u2019t reveal too much about today\u2019s circumstances, particularly as the virus has mutated significantly over this period, with the emergence of new Omicron sub-variants.<\/p>\n \u201cYou can draw a general conclusion from these data. But I think an informed conclusion would be unwise because of the complexity of the situation. The virus has changed quite substantially over that period \u2013 we\u2019re not looking at the same one through the pandemic,\u201d explains Hugh Pennington<\/a>, emeritus professor at The University of Aberdeen\u2019s School of Medicine, Medical Sciences and Nutrition.<\/p>\n Then there\u2019s the question of how accurately the data actually reflect people\u2019s mask-wearing behaviour. For instance, there\u2019s no way of being certain if the survey participants wore a mask as much as they told the ONS. While these issues are inevitable with this kind of study, some still think such flaws are significant enough to suggest that masks may still be effective.<\/p>\n As Pennington says: \u201cThe data is certainly very interesting, but it\u2019s actually quite difficult to interpret and confirm because you can\u2019t do controlled trials. You can\u2019t, for instance, infect somebody with the virus and put them in a room with people who are and aren\u2019t wearing masks and see what happens. The ONS data is quite broad brush, let\u2019s put it like that.\u201d<\/p>\n Read more about coronavirus:<\/strong><\/p>\n The ONS themselves say that different variables can affect behaviours and the likelihood of testing positive for COVID \u2013 factors which aren\u2019t represented in the data. For instance, the data doesn\u2019t reveal if somebody\u2019s workplace asked them to wear a mask in response to an outbreak. The survey also doesn\u2019t record if participants have jobs that may expose them to more COVID than usual.<\/p>\n An ONS spokesperson told BBC Science Focus<\/em>:\u00a0\u201cThese figures also come after the compulsory face mask wearing and other measures were relaxed, which may also impact our statistics.<\/p>\n \u201cAt the moment, we no longer produce the model that generates the statistics in question. In May 2022 we undertook a review and decided to pause the use of this model. However, we continually review our output and we may resume publication should it be needed.\u201d<\/p>\n It\u2019s a good question. After all, the material and structural integrity of the masks haven\u2019t changed. So what\u2019s going on?<\/p>\n According to Hunter, while non-pharmaceutical interventions \u2013 think mask-wearing and school closures \u2013 had a large impact at the start of the pandemic, their effect has lessened as the outbreak approaches a point called endemic equilibrium. This is where case numbers remain at a relatively low and constant level, with most people being infected with the virus at least once previously and receiving at least one COVID vaccine shot.<\/p>\n \u201cCase numbers will fluctuate slightly over time, but then settle to this equilibrium,\u201d Hunter explains. \u201cWe\u2019re at the point where the number of infections in the population is actually driven by how rapidly we\u2019re losing immunity from either the vaccine or previous infections, not by what we\u2019re doing to protect ourselves against the virus.\u201d<\/p>\n He adds: \u201cAs more and more people get the infection and recover, the risk changes. Many of the people you may infect<\/em> are immune, so they don\u2019t actually get infected<\/em>.\u201d<\/p>\n Another big change in the spread of COVID since the pandemic\u2019s beginning: the SARS-CoV-2 virus itself. Hunter theorises the emergence of the highly-transmissible Omicron variant also negates the protection offered by face masks.<\/p>\n \u201cOmicron is so infectious that it will spread no matter what we do,\u201d he says. \u201cThe reduction in transmission that you get with mask-wearing isn\u2019t going to be enough.\u201d<\/p>\n Earlier in the pandemic, studies indicated that wearing a face covering can, given the correct material and fit, reduce the wearer\u2019s chance of a COVID infection<\/a>. However, as the protection is limited, epidemiologists like Hunter argue that face masks effectively only delay infection \u2013 particularly with the Omicron variant now in general circulation.<\/p>\n As Keith Neal<\/a>, emeritus professor in the epidemiology of infectious diseases at the University of Nottingham, explains: \u201cThe key issue is that COVID is going to be around for years. And the best defence is vaccination and prior infection to some degree. If everyone wore masks, the rate of COVID infections would probably fall slightly. But eventually everyone is going to keep on catching it, depending on who they meet.\u201d<\/p>\n Some research has also demonstrated how masks may only delay inevitable infections. For instance, this conclusion was reached in a US study that explored the probability children would seek care for COVID<\/a>, comparing schools with and without mask mandates across 1832 counties. Initially, schools with mask mandates were less likely to seek care for COVID, but the difference in numbers between the two groups disappeared in a few weeks.<\/p>\n Hunter says: \u201cI think \u2013 and this is a theory \u2013 that children who have never worn masks in schools are more likely to have had an infection earlier on. So by now, they are more likely to be a lot more immune than children who have always worn masks. At this point, the extra immunity balances out reduced exposure.<\/p>\n \u201cAnd if you\u2019ve been religiously wearing a mask, you are less likely to have had COVID by now. You are less likely, therefore, to have got what\u2019s called hybrid immunity \u2013 immunity from a previous infection and vaccine. That is the best immunity you can have.\u201d<\/p>\n Neal also points to how the benefits of community mixing may outweigh the need for face masks: \u201cEarly in the pandemic, while we were waiting for vaccines, masks were needed to flatten the curve and stop the use of the NHS Nightingale hospitals. Now, the benefits of social mixing and mental health should be considered.<\/p>\n \u201cTake Strep A and IGAS. We don\u2019t know why it\u2019s spread so much, but it\u2019s been suggested that people\u2019s immunity has been weakened due to a lack of mixing. The benefits of masks to the community are much less than it was because COVID is less of a threat.\u201d<\/p>\n Read more about coronavirus:<\/strong><\/p>\n While he views infection as largely inevitable, Hunter does recommend that some groups should still wear a face covering in public.<\/p>\n \u201cIf I was much older or had a health condition that put me at risk, I would continue to wear a mask because it may reduce the chance that I get infected. And there is also evidence that if you\u2019re wearing a face mask and you still get infected, you get less sick,\u201d he says.<\/p>\n \u201cThe reasons why aren\u2019t clear. But it could be because you may get a lower dose of the virus if exposed to it and you\u2019re wearing a mask \u2013 and the higher the dose, generally the more sick you become.<\/p>\n He adds: \u201cI think face masks continue to have an important role. I just don\u2019t think the evidence supports mask mandates as being effective. But it\u2019s still important for certain people, particularly the vulnerable, to continue wearing face masks.\u201d<\/p>\n However, other scientists argue that all adults should wear masks in certain settings to protect themselves and others.<\/p>\n \u201cI think the public health advice has to be in favour of masks,\u201d says Prof Christopher Dye<\/a>, epidemiologist and public health expert at the University of Oxford, and former director of strategy at the World Health Organisation (WHO). \u201cYou really don\u2019t want to get infected so you can protect yourself from future infections. Even now it\u2019s not a good idea to get COVID.<\/p>\n \u201cThere\u2019s a risk it doesn\u2019t get easier with later infections. You can get it three times and the third time could be the time you get a really nasty infection with unpleasant consequences. There are millions of people with extensive and extended symptoms from this virus.<\/p>\n \u201cThere\u2019s no real need to wear a mask in an open high street, but in enclosed, high-risk settings, it is simply sensible.\u201d<\/p>\n He adds: \u201cI think the way to maintain immunity is through vaccine development and vaccine immunity. And I still don\u2019t think gaining immunity through natural infection as a deliberate strategy is a good idea. Those most at risk are vulnerable and older people. And we need to look after them.\u201d<\/p>\n Doubtlessly, there is a debate on the benefits of wearing a face mask in public indoor settings if you don\u2019t have flu or COVID symptoms yourself. But most scientists do suggest wearing a mask in indoor public settings if you are displaying symptoms, as per UK Health Security Agency (UKHSA) guidance.<\/p>\n \u201cIt\u2019s really just very straightforward. It\u2019s got nothing to do with going back to lockdown rules. It\u2019s purely risk reduction \u2013 like how you don\u2019t sneeze directly into somebody\u2019s face when they\u2019re looking at you. If you\u2019ve got respiratory symptoms and you have to go out, wearing a mask is a public service!\u201d says Pennington.<\/p>\n Paul Hunter<\/strong><\/a> is a professor in medicine at the University of East Anglia\u2019s Norwich Medical School. His research covers the epidemiology of emerging infectious disease, especially that linked to environmental factors. He has conducted epidemiological studies in the UK and around the world.<\/p>\n Thomas Hugh Pennington<\/strong> <\/a>is an emeritus professor at The University of Aberdeen\u2019s School of Medicine, Medical Sciences and Nutrition. He led the Pennington Group enquiry into the Scottish Escherichia coli outbreak of 1996 and was appointed a Commander of the Order of the British Empire for services to microbiology and food hygiene in 2013.<\/p>\nDoes everyone agree with this finding?<\/strong><\/h2>\n
But why would wearing face masks not be as effective at controlling case numbers?<\/h2>\n
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