On 7 April 2020 I wrote the piece "Should I wear a Mask?" (click here to read.)
At the time everybody seemed to be talking about wearing, or not wearing, a mask and three months later it seems little has changed. The main headline on the BBC News website at the time of writing is "Coronavirus: Face masks and coverings to be compulsory in England's shops" which contradicted what some government ministers had said just 24 hours earlier. (1) (2)
Meanwhile in the USA mask wearing has become embroiled in politics in the run-up to the presidential election. (3) (4)
Why are we now being told to wear a mask?
There has been very little in the way of true scientific advancement on the role of face masks in controlling COVID-19 but a plethora of opinions from politicians and scientists alike. It is not ethical to carry out a trial where some people are assigned to not wear masks in the face of a pandemic so scientists cannot garner information from randomised controlled trials. Instead real life scenarios have to be studied comparing infection rates between places with different mask wearing policies to see if there is a distinct difference in patterns of disease. These findings, along with the results of experiments on masks to see how effectively they block particles, then help guide policies around mask wearing. It is because different researchers can reach different conclusions that the debate around mask wearing continues to cause confusion. (5) (6)
The one area that remains definitive is that front line healthcare workers need medical grade masks as part of their PPE (Personal Protective Equipment). This is not negotiable as they are directly and repeatedly exposed to the virus. The public should not be buying medical grade PPE masks, these are needed for front line staff who are at far higher risk of coming into contact with the virus.
The WHO (World Health Organisation) states that the current evidence still suggests that COVID-19 primarily spreads between people through droplet spread. (This is explained in detail in my previous piece on masks here along with other possible transmission routes.) (7)
People in close contact (within one metre) with an infected person are the most likely to come into contact with the droplets when that person coughs or sneezes which is why social distancing remains an essential way of controlling the virus.
When remaining one metre away is not possible the advice is to wear masks to protect others (see below for further explanation of this).
The WHO has acknowledged there is emerging evidence that the coronavirus may also spread through tiny particles suspended in the air, this is aerosol spread. This is most likely in indoors settings and exacerbated by crowded and poorly ventilated settings. There have been outbreaks of COVID-19 in closed settings such as restaurants, nightclubs, places of worship and work places.
Benedetta Allegranzi is the WHO's technical lead for infection prevention and control and she has said that "airborne transmission of the coronavirus in crowded, closed, poorly ventilated settings...cannot be ruled out". (8)
This is why widespread use of masks in indoor public spaces is now being implemented in many countries across the world and in the UK.
Wear a Mask to Protect Others.
There seems to be a contradiction in the advice about wearing masks as we are told we should wear a mask to protect others BUT that wearing a mask does not protect the wearer. (9)
So that begs the question - If the virus cannot get out when someone coughs or sneezes through their mask, how does the virus get in through the same mask if someone not wearing a mask coughs or sneezes on the wearer?
A quick answer is "through the eyes." If an infected person not wearing a mask sneezes or coughs into the face of another, mask wearing person the virus can still enter their body through their eyes. Or the virus may hit the mask of the other person and, unless the mask is disposed of correctly, the mask itself becomes the source of contamination to the wearer. (10)
However, the main reason for wearing masks is to try and prevent the asymptomatic, but infected, person from infecting others.
We now know that people can have COVID-19 and be symptom-free yet still spread the virus. This may be a contributing factor to the role of so called super-spreaders who infect a disproportionate number of people. These people may breathe out a virus laden aerosol on exhalation. They don't cough an aerosol - because by definition they have no cough as they are symptom free. By wearing a mask these people may decrease their risk of transmitting the virus to other people. As we do not know who is an asymptomatic carrier unless the entire population can be tested for COVID-19 we have to have a blanket rule of masks for all. (11) (12)
Until we have a vaccine or cure for COVID-19 our ways of controlling the virus remain primarily behavioural - isolating people with the infection and their contacts, continued social distancing, frequent hand washing and mask wearing.
Masks are not a substitute for social distancing and hand washing but they are an additional measure to try and stop the virus from spreading. A colleague likened them to bullet proof vests - they don't stop all bullets but in war zones people opt to wear one if they can.
(10) file:///C:/Users/Helen/Downloads/WHO-2019-nCov-IPC_Masks-2020.4-eng.pdf
(12) https://theconversation.com/a-few-superspreaders-transmit-the-majority-of-coronavirus-cases-139950
