Wearing face masks to reduce the spread of Covid-19?

The wearing of face masks has been a contentious issue around the world since the Covid-19 pandemic started to spread early this year. It’s easy to cherry pick advice or research that supports or advises against the wearing of masks by the general public. Here’s a series of items that show how advice varies and has changed over the last few months.

Picking up on some links posted from here – Perhaps we should check the science on masks I did some checking.

18 October 2016: Why Face Masks Don’t Work: A Revealing Review

Studies of recent diseases such as Severe Acute Respiratory Syndrome (SARS), Middle Eastern Respiratory Syndrome (MERS) and the Ebola Crisis combined with those of seasonal influenza and drug resistant tuberculosis have promoted a better understanding of how respiratory diseases are transmitted. Concurrently, with this appreciation, there have been a number of clinical investigations into the efficacy of protective devices such as face masks. This article will describe how the findings of such studies lead to a rethinking of the benefits of wearing a mask during the practice of dentistry. It will begin by describing new concepts relating to infection control especially personal protective equipment (PPE).

That’s specific to dentistry and nearly four years ago so not referring to Covid.

That’s from 12 March. It’s easy to cherry pick mask wearing advice, but it’s far from clear what is best.

From 23 April: Face masks could increase risk of infection, medical chief warns

England’s deputy chief medical officer, Dr Jenny Harries, said the issue of whether members of the public should wear face masks was “difficult”.

Dr Harries told ITV’s Good Morning Britain that “the fact that there is a lot of debate means that the evidence either isn’t clear or is weak.

“The points where we are absolutely clear that face masks are needed are if you are a patient and are symptomatic -that’s stopping the infection at source from moving on to other people – and if you’re a healthcare worker and social care worker we must preserve our face masks particularly for them, to protect them.

“But when it comes to the general public it starts to get much more difficult.

“In some countries where the public are using them they are nearly always alongside other social distancing measures so it is quite difficult to tease out what the effect of the mask might be.”

Asked whether the public should be wearing them, Dr Harries said: “The number one thing is we must leave our medical masks, if you like, for those people that need them at the front line because there is clear evidence that that is beneficial.”

From 23 April: Use of face masks by general public perfectly reasonable, says GP leader

Wearing face masks or face coverings in public is “perfectly reasonable”, a GP leader has said as England’s deputy chief medical officer admitted it was a “difficult issue”.

Ministers have so far rejected calls for face masks or face coverings to be used outside healthcare settings despite other countries, including the US and Germany, recommending them.

England’s deputy chief medical officer, Dr Jenny Harries, said the issue of whether members of the public should wear face masks was “difficult”.

Dr Harries told ITV’s Good Morning Britain that “the fact that there is a lot of debate means that the evidence either isn’t clear or is weak.

“The points where we are absolutely clear that face masks are needed are if you are a patient and are symptomatic -that’s stopping the infection at source from moving on to other people – and if you’re a healthcare worker and social care worker we must preserve our face masks particularly for them, to protect them.

“But when it comes to the general public it starts to get much more difficult.

“In some countries where the public are using them they are nearly always alongside other social distancing measures so it is quite difficult to tease out what the effect of the mask might be.”

Asked whether the public should be wearing them, Dr Harries said: “The number one thing is we must leave our medical masks, if you like, for those people that need them at the front line because there is clear evidence that that is beneficial.”

From 6 May: Top scientific advisers quizzed by MPs on immunity, face masks, testing and lockdown

He and Deputy Chief Medical Officer for England Dr Jenny Harries faced a grilling from MPs during the lengthy committee appearance which offered up some revealing details, but raised more questions than answers.

Sir Patrick said the evidence of the effectiveness of wearing face coverings in public was “not straightforward” but added they could have a “marginal but positive” impact on reducing the spread of the virus.

From 29 May: Face masks essential in combating asymptomatic spread of SARS-CoV-2 aerosols and droplets

Wearing masks can reduce the airborne transmission of the novel coronavirus, a new study finds. The research is published in the journal Science.

The team of researchers at the University of California San Diego and the National Sun Yat-sen University in Kaohsiung, Taiwan, identified that wearing masks is essential to combat the asymptomatic spread of aerosols and droplets.

Masks are effective in reducing the airborne transmission of SARS-CoV-2. Properly fitted masks provide an effective physical barrier to reduce the number of viruses in the exhaled breath of asymptomatic carriers or the “silent shedders.”

“Infectious aerosol particles can be released during breathing and speaking by asymptomatic infected individuals. No masking maximizes exposure, whereas universal masking results in the least exposure,” the researchers explained.

The U.S. Centers for Disease Control and Prevention (CDC)recommends wearing cloth face coverings in public settings where other social distancing measures are hard to maintain, including pharmacies and grocery stores.

“It is critical to emphasize that maintaining 6-feet social distancing remains important to slow the spread of the virus.  CDC is additionally advising the use of simple cloth face coverings to slow the spread of the virus and help people who may have the virus and do not know it from transmitting it to others.  Cloth face coverings fashioned from household items or made at home from common materials at low cost can be used as an additional, voluntary public health measure,” the CDC said on its website.

From 29 May:  The Right-Wing Masks Theory That Lives On in Colorado

Wearing masks in Colorado during the COVID-19 pandemic has become thoroughly politicized, with those loyal to conservative beliefs in the state infinitely more likely to follow President Donald Trump’s lead in declining to don facial coverings.

Why? The most common refrain is that mask use infringes on individual choice. But it’s often accompanied by claims that facial coverings are actually dangerous to those wearing them, complete with medical assertions that may actually sound reasonable to those of us who aren’t doctors or play one on TV. And indeed, assorted officials and physicians have offered occasional support for the theory over recent months.

Trouble is, according to the Colorado Department of Public Health and Environment, it’s utter bullshit.

Cut to mid-March, when Dr. Jenny Harries, England’s deputy chief medical officer, contended that wearing face masks can increase an individual’s viral load whether one is symptomatic or not. “For the average member of the public walking down a street, it is not a good idea,” she argued.

What tends to happen is people will have one mask. They won’t wear it all the time, they will take it off when they get home, they will put it down on a surface they haven’t cleaned,” and if they don’t clean their hands often enough, they can get infected by touching either the mask or parts of their face around it.

Of course, washing a cloth mask daily largely eliminates this issue — and that’s precisely what Governor Jared Polis recommended on April 3, when he encouraged Coloradans to wear a facial covering whenever they leave home — shortly before the federal Centers for Disease Control and Environment did likewise for the country as a whole.

Nonetheless, the suggestion that mask wearers are slowly killing themselves lives on. But the CDPHE’s response to Westword on the subject makes it clear that the department thinks it has approximately zero credibility.

“Masks do not increase the viral load for people who wear them,” states spokesperson Ian Dickson. “If you are infected with the virus that causes COVID-19, that means the virus has already made a home for itself in your cells and is busy making more of the virus. ‘Shedding’ is just a byproduct of that infection.”

Dickson adds: “Once you are infected, breathing doesn’t result in an increase in the amount of virus in your body, whether you have a mask on or not. Wearing a face mask helps minimize the spread of the virus, so everyone should wear a mask when out in public.”

3 June: Mixed messaging on wearing masks is a major public health failure

The World Health Organization (WHO) unequivocally warns against wearing face masks, unless you are either displaying symptoms or taking care of a patient infected with COVID-19. Full stop. No face masks. No grey area.

An April 17 article in the Journal of the American Medical Association (JAMA) advises, “ … nonmedical masks may not be effective in preventing infection for the person wearing them.”

Clinical evidence suggests that cloth masks contribute to viral infection, a study of non-medical masks by the University of New South Wales reported in Science Daily. “The widespread use of cloth masks by health-care workers may actually put them at increased risk of respiratory illness and viral infections and their global use should be discouraged. The penetration of cloth masks by particles was almost 97 per cent compared to medical masks with 44 per cent.”

The WHO cautions against wearing face masks, the CDC recommends them; “CDC recommends wearing cloth face coverings in public settings where other social distancing measures are difficult to maintain (e.g., grocery stores and pharmacies) especially in areas of significant community-based transmission.”

The deputy chief medical officer of England advises against, Health Canada recommends for; “Wearing a homemade non-medical mask/facial covering in the community is recommended for periods of time when it is not possible to consistently maintain a two-metre physical distance from others, particularly in crowded public settings, such as stores, shopping areas and public transit.”

Who to believe, then?

From 12 June:  Compulsory use of facemasks in shops and public transport can slash spread of coronavirus by 40%, study claims

Making face masks compulsory could slow the spread of Covid-19 by as much as 40 per cent, a study suggests.

Researchers assessed the effect face coverings had on regional epidemics in Germany when they were made mandatory in shops and public transport in April.

The move slashed the number of new infections over the next 20 days by almost a quarter, rising to 40 per cent after two months.

The scientists said their study provided ‘strong and convincing statistical support’  that masks ‘strongly reduced the number of incidences’.

Writing in the study, published as a discussion paper for the Institute of Labour Economics, the scientists write: We believe that the reduction in the growth rates of infections by 40 per cent to 60 per cent is our best estimate of the effects of face masks.

It is the most compelling evidence yet for mandatory mask-wearing in the UK, where the Government is still concerned face coverings might do more harm than good.

The UK Government’s scientists insisted throughout the crisis there is no evidence face masks prevent the spread of the virus.

But they changed their tune last week and made it compulsory for people to wear masks on public transport in England, threatening to dish out fines to those who don’t comply.

3 July: Coronavirus: where and when do you need a face covering?

  • Face coverings to become mandatory in shops in Scotland from 10 July. They are already mandatory on public transport.
  • Face covering to become mandatory on public transport in Northern Ireland form 10 July.
  • Wearing a face covering is already mandatory in hospitals and on public transport in England.
  • Ride-sharing company Uber has made face coverings mandatory for both passengers and drivers across the UK.
  • Separately, the World Health Organisation (WHO) has changed its global guidance on face masks, suggesting that in circumstances where social distancing is difficult – such as public transport, shops etc – basic medical masks (not respirator masks) should be worn by the over 60s, and homemade three-layer masks should be worn by the general public.

Elsewhere, many countries have encouraged or made mandatory the wearing of face masks by the public.

Some, such as Austria, Slovenia, Bulgaria, Poland, Singapore, and Turkey – have made wearing face masks mandatory in public.

In the US, China, Japan, France, India, Canada, Germany and Brazil, wearing homemade masks in public or in certain situations, such as on public transport, is encouraged but not enforced.

The World Health Organisation (WHO) originally said that healthy people only needed to wear a mask if they were taking care of a person with COVID-19, and cautioned about the risks of mask-wearing instilling a false sense of security in the wearer and leading to them becoming lax about crucial measures such as social distancing and handwashing.

It also said that ‘non-medical or cloth masks could increase potential for COVID-19 to infect a person if the mask is contaminated by dirty hands and touched often, or kept on other parts of the face or head and then placed back over the mouth and nose.’

But it has now updated its advice on face masks, saying that governments should encourage the general public to wear masks in situations where social distancing isn’t possible, such as on public transport and in shops. It advises a home-made three-layer mask for most people, and that the over-60’s consider wearing ‘medical’ masks in areas with high rates of community transmission.

The European Centre for Disease Control (ECDC) suggests that homemade masks may be useful to help prevent the spread of coronavirus by asymptomatic people in confined spaces, but acknowledges the evidence for this is currently weak.

All are clear that higher-grade medical respirator masks should be reserved for frontline health workers, where they are needed most.

Face masks: what’s the evidence for them?

A meta-analysis of nearly 1,000 studies around influenza transmission by Professor Ben Cowling, Head of Epidemiology and Biostatistics at Hong Kong University, found that the use of face masks, in combination with hand hygiene, was more effective against laboratory-confirmed influenza than hand hygiene alone.

Dr Christopher Hui, Clinical Assistant Professor at Hong Kong University and Honorary Consultant in Respiratory and Critical Care Medicine at the Royal Free Hospital London, says: ‘We believe that face masks help prevent droplet and aerosol spread primarily by capturing the droplets as they exit our airways at velocity when coughing, sneezing or talking at volume.’

The change in UK government advice has come after ‘careful consideration of the latest scientific evidence from the Scientific Advisory Group for Emergencies (SAGE).’

Previously, Deputy Chief Medical Officer Jenny Harries said the fact that the issue has been debated at length by the UK government’s scientific advisors suggests that the evidence isn’t quite so clear, whereas the evidence for measures such as hand hygiene and social distancing is more solid.

Hand washing and social distancing remain the most important actions to take to protect yourself and others from coronavirus.

This all doesn’t matter here in New Zealand for the general public in public places, as we don’t have any detected community transmission.

Current Ministry of Health advice: COVID-19: Use of face masks in the community

Face masks are one part of Infection Prevention and Control (IPC) measures used in health care settings.

There is no convincing evidence one way or other to require the use of non-medical face masks for healthy people in the community to protect from COVID-19. There are potential benefits and potential risks with such use. Countries are taking different approaches based on their current COVID-19 context.

Non-medical masks could provide an additional element of protection in preventing someone who is infectious with COVID-19 spreading this infection to others.

Non-medical masks are not proven to effectively protect the person wearing them from becoming infected by others. They are therefore not a substitute for basic hygiene measures and physical distancing, where possible and practical. Some of the reasons for this include the types of materials used for the masks and how they are worn.

Going by the above evolution of advice this sounds a bit dated. If Covid starts to spread here again this may change.

This post is not intended to be advice on whether to wear a face mask or not, it was an exercise in how research and advice has varied and changed over the last four months.

All but the first and last links above were found via Google searching for: Jenny Harries face masks

Previous Post
Leave a comment

11 Comments

  1. Alan Wilkinson

     /  4th July 2020

    Don’t share enclosed spaces with infected people and wash hands after touching things that may be infected seems to be the gold standard protection.

    Once you comromise that a mask may be a minor benefit but mostly to others if you are infected and don’t know it.

    Reply
  2. Pink David

     /  4th July 2020

    The most entertaining, and informative, part of masks is the fact the discussion is happening now.

    Scotland is making masks compulsory on the 9th July. Next week.

    Not three months ago
    Not last week

    Covid is over in Scotland, this rule comes in after any use for them has gone.

    Comical.

    Reply
    • Pink David

       /  4th July 2020

      Just to be clear too, the Scottish requirement is ‘face covering’. Anything at all over your face.

      Reply
      • So a lace veil would do ???

        Reply
        • Pink David

           /  4th July 2020

          Correct

          Reply
          • Gezza

             /  4th July 2020

            Only if you were complete moron.

            Reply
            • The people I saw wearing them under their noses or even under their chins here would have been as well off with a veil.

            • In fact, they’d have been better off, as they wouldn’t have been touching the veil all the time. And a paper mask is surely all but useless.

            • Pink David

               /  4th July 2020

              “Only if you were complete moron.”

              “By face coverings we do not mean a surgical or other medical grade mask but a covering of the mouth and nose that is made of cloth or other textiles and through which you can breathe, for example a scarf or religious head covering that covers the mouth and nose.”

              Lace is a textile through which you can breathe. It meets the requirement of the law.

  3. Pink David

     /  4th July 2020

    This applies to NZ as well.

    “Sunetra Gupta, professor of theoretical epidemiology in the Department of Zoology at the University of Oxford, says Australia is adopting a “selfish’’ and “self-congratulatory’’ approach which is misguided and will have negative long-term consequences and urged the country to look at the latest evidence to decide its tactics.”

    https://www.theaustralian.com.au/nation/oxford-epidemiologist-pushes-herd-immunity/news-story/cf019113ea52916f64a16dcad96095a8

    Reply
  4. Alan Wilkinson

     /  4th July 2020

    Seems that protecting properly the lowest paid workers in hospitals and rest homes would have yielded the best outcomes:
    https://www.telegraph.co.uk/news/2020/07/03/nhs-cleaners-porters-coronavirus-super-spreaders-hospitals-data/

    Reply

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s