1. Do masks help?
Cultural differences are always interesting, and I’m defining culture as ‘the way we do things around here’. One such difference that has leapt to the foreground during this pandemic is whether we wear masks or not. In many far eastern societies it is taken as normal that as soon as you have symptoms of a cold, flue, or something nastier you cover up with a mask when you go out. The reason is to stop infecting others – it’s your responsibility to protect other people. But in the UK and Europe generally wearing masks is more likely to provoke staring and smirking. A visit to the Co-op this week had exactly that effect – although it was a minority of those present I’m pleased to say. Yes, I wear a mask when enter shops. To me its a no-brainer and I have been puzzled by the advice we have been given on the subject. Am I wrong?
What is the evidence on masks and does it square with the official advice? That advice has been pretty clear up to now – don’t bother with masks, just wash your hands and stay 2 meters apart.
WHO “If you do not have any physical symptoms, such as fever, cough or runny nose, you do not need to wear a medical mask. Masks alone can give you a false feeling of protection and can even be a source of infection when not used properly.” Dr. April Baller WHO Health Emergencies Programme (Ref 1).
CDC: “If you are NOT sick: You do not need to wear a facemask unless you are caring for someone who is sick (and they are not able to wear a facemask). Facemasks may be in short supply and they should be saved for caregivers” (Ref 2).
US Surgeon General: “Seriously people – STOP BUYING MASKS! They are NOT effective in preventing general public from catching #Coronavirus, but if healthcare providers can’t get them to care for sick patients, it puts them and our communities at risk!” (Ref 3).
UK Deputy Chief Medical Officer (Dr Jenny Harries): “If a healthcare professional hasn’t advised you to wear a face mask, it’s usually quite a bad idea. People tend to leave them on, they contaminate the face mask and then wipe it over something. So it’s really not a good idea and doesn’t help” (Ref 4).
The arguments against masks are:
1. A mask gives a false sense of security
2. Transmits infection by not being used correctly
3. Depriving medical staff of scarce resources
One of the best sources of evidence based medical research is the Cochrane reviews. These follow strict protocols looking at all the data available. Two reviews on masks have been undertaken in 2011 and 2020. In the 2011 (Jefferson et al. “Physical interventions to interrupt or reduce the spread of respiratory viruses. 2011” )(Ref 5) The key data is presented as a table shown below:
The Effect size is given as an odds ratio for 9 interventions. The smaller the number the greater the positive effect. All the interventions had a statistically significant result. The effect size indicates how low was the chance of infection. So, N95 masks – the ones used in hospitals came out best (0.17) and wearing a mask was also well worth it.. And wearing a mask is more effective than just washing hands (11 times a day!). Clearly the best strategy is to COMBINE these interventions – Gloves, mask, handwashing and eye protection.
The 2020 review was a follow up on the first metaanalysis. (Burch & Bunt. Can physical interventions help reduce the spread of respiratory viruses? 2020) This paper concluded
The best evidence (moderate certainty) was for handwashing plus masks.
Why wouldn’t the results show that mask are effective when they are taken for granted in a medical setting? The evidence then supports the wearing of masks as they provide real protection. Of course its not perfect protection but lets not allow the perfect to be the enemy of the good.
The second point is that you have to handle masks carefully or they spread infection. So we should wash our hands after taking the masks off? Of course Why is that a greater risk for members of the public compared to medical staff? Not clear. Take the mask off carefully lay it on a disposable paper towel. Use this to place it in the washing machine – Ill get to this in a moment – and wash your hands after putting the paper towel in an appropriate bin. Yes you can re-use masks if kept for personal use and washed after each use. Best washed at a high temperature.
Final question is about what mask to wear. This is irrelevant to the primary question of do masks work. If they do then we should use them. If you don’t wish to use medical masks because of the concerns over the supply chain then do as I do and make your own. Or just cover your face with a closely woven fabric – yes its that simple and CAN cut transmission by up to 50% – our way our of lockdown!
Here are some ideas:
My preferred option is made from a HEPA vacuum bag. The filtration is better than the N95 respirators (the ones used by the NHS):
However lots more options are available and a good place to start is #Masks4All (ref: 7) good luck and meet me (at 2m separation!) in the Co-op wearing your mask!
More to follow. Watch this space.
A recent update has begun to strengthen the case for wearing masks/face coverings in places where social distancing is difficult (public transport?) or places of work. A recent study from the University of Hong Kong has made a strong case for covering up to protect others and also ourselves. Have a look at this summary from Dr. John Cambell:
Ref 1: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/when-and-how-to-use-masks
Ref 2: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html?
Ref 3: https://twitter.com/surgeon_general/status/1233725785283932160
Ref 4: Dr Jenny Harries with the Prime Minister, Boris Johnson, at 10 Downing Street, March 11th, 2020. https://twitter.com/10DowningStreet/status/1237760980450451456
Ref 5: Jefferson et al. Physical interventions to interrupt or reduce the spread of respiratory viruses. Cochrane Database Syst Rev. 2011. https://www.ncbi.nlm.nih.gov/pubmed/21735402
Ref 6: Burch & Bunt. Can physical interventions help reduce the spread of respiratory viruses? 2020 https://www.cochranelibrary.com/cca/doi/10.1002/cca.2965/full
Ref 7: https://masks4all.org/story