Last Wednesday, the National Public Health Emergency Team (NPHET) widened the indications for the use of surgical masks for frontline staff.
They should now be worn by healthcare workers when providing care to patients within two metres of that patient, for all encounters of 15 minutes or more, and when interacting with other healthcare workers in the workplace where a distance of two metres cannot be maintained.
This announcement is as welcome as it is long-awaited. Yet despite the recommendation by both the Chinese and American Centres for Disease Control, neither the World Health Organisation nor the Irish health authorities have yet to recommend cloth face coverings for members of the public in enclosed public spaces.
Social distancing is the essential strategy for the control of any infectious disease, especially respiratory infections. Good hand hygiene is also important. In addition, many countries encourage cloth face coverings for people in public areas.
Face coverings could reduce the amount of droplet expelled from a person’s nose and mouth, and may help reduce the spread of the virus. The hypothesis is that face masks mostly protect other people, not the mask wearer, and only have full beneficial effect if everyone in society wears them.
Pre-symptomatic spread is now considered a major factor in the spread of Covid-19. People infected with the virus may pass the infection onto others up to three days before they begin to show any symptoms. A recent article in the journal Nature estimated that 44 per cent of secondary cases were infected during the index cases’ pre-symptomatic stage. The journal Science puts this figure at 50 per cent.
The amount of virus exposure at the start of infection (the infectious dose) may determine the severity of the illness. Those exposed to a high dose of virus at the beginning may suffer more symptoms and be at risk of a worse outcome.
Conversely, those who initially come into contact with a smaller dose of virus may experience milder symptoms. Some evidence suggests an association of viral dose with severity of the disease. However, as with many aspects of SARS-CoV-2, this is not certain. Cloth face coverings may help reduce the spread of the virus from those who show no symptoms and may decrease the initial dose in those who are exposed to it.
Health authorities in parts of Asia have encouraged all citizens to wear masks in public to prevent the spread of the virus, regardless of whether they have symptoms. Last month George Gao, director of the Chinese Centre for Disease Control and Prevention, said “he big mistake in the US and Europe” was that people were not wearing masks.
Soon afterwards, the American CDC updated its guidance and now recommends wearing “cloth face coverings in public settings where other social distancing measures are difficult to maintain”.
Some European countries have made it mandatory for people to cover their nose and mouth in public spaces. The Czech Republic, Bulgaria, Bosnia, Israel and Turkey now enforce this requirement. In Austria, a country already relaxing restrictions, masks are handed out before entry into supermarkets.
Surgical masks are in short supply in the Czech Republic, prompting a grassroots drive for home made face masks. Uplifting videos have appeared on Twitter and YouTube showing wonderful ingenuity of design using interesting material like hoover bags, coffee filters and old finely woven cloths. The American CDC recommends using multiple layers of fabric such as old t-shirts or bandanas.
It is important that people wearing cloth face coverings or face masks refrain from touching their face, and that home made masks are regularly washed in a 60 degree cycle.
In Ireland some people have been wearing surgical-type masks in public places. This has caused anger in others due to the shortage of face masks for healthcare workers.
It is important to recommend surgical face masks for healthcare workers and home made masks for everyone else. However, let’s not show anger towards people wearing surgical-type face masks. After all, these masks are freely available.
Many pharmacies in Ireland stock them. They can be purchased on Amazon, albeit at a premium. A mask worn by a member of the public does not necessarily mean there is one less for a healthcare worker. It is the employer who has a duty of care to the employee.
Some 26 per cent of confirmed coronavirus cases in Ireland are among healthcare workers. It is vital that they have all the personal protective equipment they require. All professions in close contact with the public such as gardaí and shop assistants should be encouraged to wear face masks to protect themselves and the public.
The precautionary principle can be defined as “a strategy for approaching issues of potential harm when extensive scientific knowledge on the matter is lacking”. The evidence base on the usefulness of cloth face coverings in reducing the spread of respiratory infections is sparse and contested, but Covid-19 is a serious illness that currently has no known treatment or vaccine.
A recent article in The British Medical Journal advocates that “policy makers apply the precautionary principle now and encourage people to wear face masks on the grounds that we have little to lose and potentially something to gain from this measure”.
Dr Domhnall Heron is a GP based in Leitrim