Face coverings: Fad or necessity?
“We are recommending that you consider using face coverings…as a precautionary measure.”
So said the guidance from the Scottish Government issued on 28th April. However the recommendation stresses that “evidence on the use of face coverings is limited, but there may be some benefit in wearing a facial covering when you leave the house and enter enclosed spaces, especially where physical distancing is more difficult and where there is a risk of close contact with multiple people you do not usually meet. Examples include, traveling on public transport or entering a food shop where it is not always possible to maintain a 2 metre distance from another customer. There is no evidence to suggest there might be a benefit outdoors, unless in an unavoidable crowded situation, where there may be some benefit.”
The type of face covering suggested, as a precautionary measure, is not a”surgical or other medical grade mask but a facial covering of the mouth and nose, that is made of cloth or other textiles and through which you can breathe, for example a scarf.”
The guidance is being issued: “As some people can have the virus but experience no symptoms (asymptomatic infection), wearing a face covering in the situations outlined above may provide some level of protection against transmission to other people in close proximity.”
Studies show that people infected by Sars-Cov-2, the cause of Covid-19, were “shedding” most viruses (so possibly infecting someone else) just before or at the time symptoms first appeared, often in very mild form. However, at present the public use of facial coverings is not being made mandatory and will not be enforced at this stage, but will be kept under review.
In an article in the Guardian, Babak Javid, Professor at the Tsinghua University School of Medicine in Beijing and a consultant in infectious diseases at Cambridge University hospitals, writes:. “We know that even normal speech can spread droplets, and this is dramatically reduced by the use of cloth masks. And for symptomatic people infected with common-cold coronaviruses and influenza, normal breathing also results in shedding of virus, which again, is blocked by wearing a mask. While we don’t know for sure how contagious a truly asymptomatic Covid-19 patient might be, evidence suggests that around 40% of cases of transmission arise from people without symptoms.
Although, according to Professor Javid, there have been a small number of trials looking at masks for preventing influenza, results were disappointing. But in studies for the other measures strongly promoted by the UK and devolved governments, measures such as hand-washing, evidence has been similarly disappointing. For other measures, such as the two-metre rule, or lockdowns, there have been no trials at all. “So masks seem subject to a different standard of evidence than other measures. And while controlled trial data is not available, “natural experiments” do suggest at least a correlation between mask-wearing and reduced Covid-19 transmission. The city of Jena in Germany introduced mandatory mask-wearing on 31 March and recorded no new infections for eight days, while surrounding cities continued to see a rise.”
The Scottish Government’s face covering guidance has predictably sent the media and unionists into wildly indignant overdrive, accusing the First Minister of wanting to rile the newly returned to duty Prime Minister by having different guidelines north and south of the border. The media insisted this would send contradictory messages, although Scotland varies in many ways from England, having our own legal system, education, church and NHS. Minimum pricing for alcohol is also only operational in Scotland. Further fuel was added to the media ire when the UK government decided the weakness of the evidence for wearing masks or face coverings did not merit their use by the public.
The broadcast media trotted out their old faithful, octogenarian Hugh Penningston, emeritus professor of bacteriology (so not a virologist) at the University of Aberdeen (retired for 17 years), to pour cold water on the guidance, saying there was insufficient information to support the use of face masks/coverings.
Interestingly, Devi Sridhar, Professor (current, not long retired as Professor Pennington) and Chair of Global Public Health at Edinburgh University Medical School, tweeted her support of the Scottish Government’s guidance: “Positive move in Scotland to have face coverings when 2 m physical distancing hard to maintain. This does not mean buying medical masks. Instead covering face with scarf/bandana/home-made cloth mask. Largely to protect others from you & vice-versa.”
More than 30 countries, including Germany (facing a spike in infections and possibly having to again impose strict lockdown) have made mask wearing compulsory, often with large fines imposed for not complying. And Irish Taoiseach, Leo Varadker, has said the Irish Government is considering changing its advice to the public on the use of face coverings, suggesting this could be done by the end of this week. “On the issue of face coverings and I’m going to say face coverings instead of face masks because we want to make sure that face masks are preserved and protected for our healthcare staff and those who need them the most, but the issue of advising people to wear face coverings is under consideration at the moment.”
Such is the range of the internet that it wasn’t long before two graphics started appearing on social media. This one used by America’s Center for Disease Control and others.
This graphic’s statistics have been deemed by some as unreliable as it is based on evidence from other airborne diseases, not COVID–19, and therefore is not verifiable. However others, whilst accepting the figures quoted may not be totally reliable, counter this by saying the principle is the same. Masks hinder the transmission of airborne spray carrying the virus from person to person.
The second infographic is a country by country comparison of coronavirus trajectories by the FT in which mask wearing and non mask wearing countries have been indicated by someone unknown. This has been dismissed as simplistic as other measures such as the stringency of the lockdown, strictness of social distancing, school closures, and cancellation of public events need to be taken into consideration. However a study was carried out between Austria and the Czech republic where social distancing requirements were introduced on the same date, but the Czechs also introduced mandatory mask wearing. The Austrian case rate continued its upward trajectory, whilst the Czech’s flattened out. It wasn’t until Austria also introduced mask laws weeks later that the two countries returned to similar trajectories.
This is referred to in an article in fast.ai by Professor Trisha Greenhalgh OBE, Professor of Primary Care Health Sciences and Fellow of Green Templeton College at the University of Oxford, and Jeremy Howard, an Australian data scientist, which goes to to say:
“Debates about the effectiveness of masks often assume that the purpose of the mask is to protect the wearer, since this is what all doctors learn about in medical school. Cloth masks are relatively poor (though not entirely ineffective) at this. For 100% protection, the wearer needs a properly fitted medical respirator (such as an N95). But cloth masks, worn by an infected person are highly effective at protecting the people around them. This is known as “source control”. And it is source control that matters in the debate about whether the public should wear masks.
“If you have COVID-19 and cough on someone from 8 inches away, wearing a cotton mask will reduce the amount of virus you transmit to that person by 36 times, and is even more effective than a surgical mask. Oddly, the researchers who discovered this fact considered a 36-fold reduction to be “ineffective”. We disagree. It means you’ll transmit only 1/36th the amount of virus you would otherwise have done, decreasing the viral load, which is likely to lead to a lower probability of infection, and fewer symptoms if infected.”
Mathematical modeling by the team at fast.ai, supported by other research, suggests that if most people wear a mask in public, the transmission rate can go beneath 1.0, entirely stopping the spread of the disease. However, the mask doesn’t have to block every single viral particle, but the more particles it blocks, the more effective it is.
So, is the reluctance to promote the wearing of masks or face coverings because governments are aware of the scarcity of surgical/medical masks, or because to date no definite relationship between their use by the public and the lowering of the infection rate has yet been proven to the satisfaction of health ministers and medical officers?
For us members of the public the question now is do we wear a face covering or not? At present in Scotland that decision is being left to the individual, though that could change. But surely the assumption must be that anyone concerned by their health and the health of those close to them will willingly embrace any option that might keep them safer and hinder the spread of this horiffic virus.
