THE SCIENTIFIC VERDICT ON... MASKS

People are again wearing them on public transport. Some doctors have called for their return. But do they work? We examine ALL the evidence to deliver...

Mandatory mask-wearing in hospitals and healthcare settings was scrapped in Ireland last year. But as cases rise again, Spain announced last week that compulsory mask-wearing will be reintroduced in hospitals to ‘protect healthcare workers’. So could masks stage a comeback here too?

There is speculation about whether we’re facing another Covid wave as the highly infectious JN.1 — or Juno — causes concern.

Meanwhile, social media abounds with reports of ‘people wearing masks again’, and debate rages as to whether or not it’s now good etiquette to wear one in public spaces if you have cold-type symptoms, whatever the cause.

Some doctors think so, including A&E medic Dr Saleyha Ahsan who says everyone should don a mask to protect others and themselves from coughs and sneezes.

Now, almost four years on from those early days of the pandemic, what IS the scientific evidence — do masks really work, or not?

Q Surely by now we know if masks are effective. What is the verdict?

A Before that can be answered — and there are answers — it is important to look at why there has been so much debate and doubt about masks.

Part of the issue lies in the fact that, when the mandates were introduced there was not a great deal of reliable evidence for their efficacy.

Much of what we knew came from studying hospital workers on wards — where masking is standard practice — and mostly compared tightly fitting medical grade N95 masks with looser blue surgical masks for protection against flu viruses. No one really knew how well masks of any kind might drive down Covid transmission in everyday environments.

A number of senior public health officials in the UK and America were on record early in the pandemic saying that maskwearing wasn’t a good idea.

A 2015 study carried out in 14 hospitals in Hanoi, Vietnam (one of a handful of studies around at the time) compared reusable cloth masks to disposable medical ones. It found the fabric versions could become contaminated if not washed properly, potentially increasing the risk of infections.

But as the first wave hit, something else was discovered: Covid was transmitted by asymptomatic people. This led scientists, and, more importantly, politicians who make the rules, to broaden the search for interventions that might allow us to avoid lockdowns.

Paul Hunter, Professor of Medicine at the University of East Anglia, says: ‘Lab studies started to show masks could, theoretically, reduce Covid infections by blocking exhaled droplets of moisture containing the virus.

‘No one knew what the real-life effect would be, but recommending masks was a belt-and-braces approach.’

Q OK, so we all wore masks, it didn’t stop the pandemic, millions still died. Surely that’s proof in itself that masks didn’t make a difference?

A Professor Hunter gives the short answer: ‘Masks reduce the risk of infection by some amount, but they don’t eliminate it.

‘Some will see that as “masks don’t work” but they do have some value on an individual level.’

This is particularly relevant for vulnerable people — those with serious diseases affecting immunity, for instance — who are often recommended to wear a mask in crowded areas even outside the pandemic.

And the type of mask matters. Some viruses travel in larger droplets of saliva or mucus, coughed or sneezed out by an infected person. These don’t float in the air. They can be either directly inhaled or, commonly, picked up from surfaces by the hands, and then transferred when someone touches their face.

Other viruses — as it turned out, like Covid — are airborne or ‘aerosol’, and exist in tiny particles of moisture in our breath and floating in the air. Surgical masks provide a physical barrier against droplets. However, because these masks do not fit closely around the face, tiny airborne particles could still get to the mouth and nose.

This has been proved in lab research that looked at how particles travel through and around different types of face-covering. That’s why the tight-fitting N95 and FFP2 and FFP3 masks — the ones that look a bit like a beak and are made from several layers of dense fabric — consistently perform best in Covid protection.

A University of Cambridge study published in July 2021 suggested FFP3 masks provided ‘most likely 100 per cent protection against infection on wards’.

The study’s author, Chris Illingworth, an infectious diseases expert, wrote: ‘Once FFP3 masks were introduced, the number of cases attributed to exposure on Covid-19 wards dropped — in fact, our model suggests FFP3 may have cut ward-based infection to zero.’

However, when looked at as a populationlevel intervention, there is no real proof that masks are particularly effective in reducing respiratory infection rates.

Why? Because the effects of a single intervention such as masks are difficult to unpick. In most countries, masks were introduced alongside social distancing, hand-washing and lockdowns.

So their value, over and above these measures, in reducing infection rates on a population level remains uncertain.

The best data on masks comes from metaanalyses — reviews of the highest-quality studies to build an overall conclusion.

One, by a group of American doctors led by epidemiologist Roger Chou, which has been updated eight times as new evidence has emerged, concludes there is ‘low to

moderate strength evidence that mask use may be associated with a small reduction in [Covid] infection versus no mask.’

In summary, if you wear a well-fitting mask, you will be provided with some protection from respiratory infections and may avoid passing on anything you have. But there isn’t really any good evidence that mask mandates worked to reduce national infection rates.

Q What about those studies which have proved that masks are a waste of time?

A You are probably referring to the much-debated Danish mask study, published in late 2020 and often cited as definitive proof that masks don’t work.

It found that, in a group of around 3,000 people in Denmark asked to wear a mask, 1.8 per cent got Covid, while 2.1 per cent of a similar-sized group of people who weren’t asked to wear a mask tested positive — a difference too small to be significant.

Some scientists interpreted this as a reason to abandon mask mandates.

But the authors of the study say their findings do not prove anything about the effectiveness of mask-wearing.

Instead, their work was designed to look at whether advising people to wear masks was useful in preventing Covid spread — not the masks themselves.

Only half of those in the masked group actually wore them. The study showed that people (in Denmark, at least) aren’t very compliant and a recommendation to wear masks isn’t very helpful.

Another study often said to prove masks don’t work is a review by the respected Cochrane research charity. This looked at evidence from 78 trials involving more than 610,000 participants.

However, after it was published in January last year, Karla Soares-Weiser, editor-inchief of the Cochrane Library, wrote: ‘Many commentators have claimed that a recently updated Cochrane Review shows that “masks don’t work”, which is an inaccurate and misleading interpretation. It would be accurate to say that the review examined whether interventions to promote mask wearing help to slow the spread of respiratory viruses, and that the results were inconclusive.’

As Dr Lucky Tran, a New York-based biologist, explained: ‘The paper mixes studies conducted in different environments with different transmission risks.

‘It also combines studies where masks were worn part of the time with studies where masks were worn all the time. And it blends studies that looked at Covid with those that looked at influenza.’

Interestingly, two studies included in the Cochrane review did specifically study the protective effect of masks during the pandemic. Both found they did, in fact, protect people from Covid.

Q So should I wear a mask if I’m visiting a patient or elderly relative?

A Many doctors and virologists agree that this would be wise given the time of year and the sheer number of viruses going around at the moment.

Throughout the pandemic, rates of flu and colds fell to near-zero — an indication that the package of Covid measures, including masks, were effective against a whole range of transmissible illnesses.

Q But what about for the rest of us. As we all have some immunity to Covid now, doesn’t it makes all this fussing a bit pointless?

A It is true that most of us have immunity from Covid infections, and that the latest variants seem less severe.

If your risk of contracting Covid due to this immunity is low, the overall risk reduction that comes from wearing a mask will also be low, says Prof Hunter.

‘That doesn’t mean masks don’t work,’ he says. ‘Just that masks don’t offer much extra protection if you’re already immune.’

This is backed by a recent study at St George’s Hospital in London. This found that removing the mask policy at the height of the Omicron wave in 2022 found ‘no immediate or delayed change in infection rate’.

‘That doesn’t mean masks are worthless against Omicron,’ lead author Dr Ben Patterson said, ‘but their real-world benefit in isolation appears to be, at best, modest in a healthcare setting.’

Q That must mean there’s even less point in children wearing them?

A Yes, basically. Wearing masks has largely been deemed ineffective in preventing the spread of Covid in children.

In November 2021, NPHET recommended the wearing of face masks/coverings by children aged nine and above on public transport, in retail and other indoor public settings, as was already required at that time for children aged 13 years and over. NPHET also recommended that mask wearing should be introduced for children in third class and above in primary schools.

But a review of the British Office for National Statistics data by Prof Paul Hunter concluded masks were less effective in children.

‘Some studies show masks simply delayed the point at which children got Covid,’ says Prof Hunter. ‘Masks or not, they were going to get it eventually.’

Again, that doesn’t mean masks themselves don’t work. But few people, particularly children, wear masks 24/7 — and Covid can be picked up anywhere.

Q

So, should we wear masks or not?

A Ultimately it’s up to you. There is no legal mandate to wear a mask at the moment. None of the experts Magazine spoke to believe there is any need to return to widespread mask-wearing. But most agree it ‘makes sense’ if you are visiting someone vulnerable, particularly in hospital — and especially if you have respiratory symptoms.

Professor David Strain at the University of Exeter Medical School says: ‘There’s no need to wear a mask day-to-day. But if you’re coughing and spluttering, it might be polite to those around you to stop it spreading.’

And it may still have ‘some value’ to those who are vulnerable themselves, Prof Hunter adds. ‘Even if it doesn’t totally prevent you from getting an infection, there is some reasonable evidence that if you reduce the dose of virus you’re exposed to, you’re likely to be less severely unwell.’