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'We cannot just flatten the curve, we need to crush it. Wearing masks will help'

Professor Gerry Killeen has worked on the control of malaria and zika viruses in the past. He says we should all be wearing masks.

Professor Gerry Killeen

Professor Gerry Killeen of University College Cork has lived and worked in Africa for over 18 years, focusing on transmission dynamics and control strategies for malaria. More recently, he expanded his outreach to Haiti, where he evaluated one of the new mosquito control tools he helped develop as an option for tackling the Latin American Zika pandemic. Here, he outlines his belief that we should all be wearing non-medical masks to ensure the coronavirus curve is crushed, not just flattened.

SHOULD MASK WEARING be mandatory in Ireland now? Yes, it should, although not necessarily everywhere or all the time. Until now, the debate has been mixed around the use of masks, with our own authorities following the advice of the World Health Organization. Most people in Ireland are not in the habit of wearing masks since the lockdown began.

The advice from China around the wearing of masks, however, is pretty clear. While the Director of the Chinese Center for Disease Control and Prevention (CDC), Dr George Gao has been pretty busy with the pandemic right where it all started, he still made time for an interview with Science magazine six weeks ago so he could urgently share his expertise and experience with the outside world. When asked what mistakes other countries are making, he said the following:

The big mistake in the U.S. and Europe, in my opinion, is that people aren’t wearing masks. This virus is transmitted by droplets and close contact. Droplets play a very important role—you’ve got to wear a mask, because when you speak, there are always droplets coming out of your mouth. Many people have asymptomatic or pre-symptomatic infections. If they are wearing face masks, it can prevent droplets that carry the virus from escaping and infecting others.

While wearing a mask or other face-covering is always a good thing, that doesn’t necessarily mean masks are essential for everyone at all times and in all places. While widespread use should be encouraged, it is most important to emphasise where and when wearing a mask matters most.

Obviously, if one has tested positive or have suspicious symptoms and need to self-isolate at home, as I did, then you really should definitely wear a mask all the time to protect everyone else in the house. However, many people with Covid-19 get only mild symptoms, if any, so it’s ideal to always assume one may be quietly carrying and shedding the virus and behave accordingly.

Why wear masks? Why not?

Many of our family and friends in Tanzania and Brazil are routinely wearing home-made masks or other face coverings all the time to prevent transmission, even within their households. 

However, the really big key issue is to cut down on transmission between households and across the communities through contamination of the spaces, surfaces and goods we share with others.

There’s a wonderful video in the New England Journal of Medicine, the world’s most cited medical journal, in which the droplets coming out of someone’s mouth are clearly visualised when he says: “stay healthy!”.

It’s also very obvious how these droplets are almost entirely eliminated once the speaker wears a slightly damp washcloth over his mouth. When one also considers solid evidence that the virus can remain viable on plastic and stainless steel surfaces for up to three days, it’s easy to imagine how one might become infected by someone you’ve never met or even seen, who just happened to speak while sitting at the same table a few hours before you.

For example, there’s a small garage with a minimarket in an area I know. Most people shopping inside do so quite carefully and conscientiously. However, day in day out, I see dozens of people taking turns sitting at the unfenced table immediately outside, either enjoying the goodies they just bought or waiting for someone who has gone inside. They chat away with each other or on the phone. Then they head off and a few minutes later someone else sits down.

It becomes very easy to understand how community transmission occurs, like that documented by some Chinese studies showing transmission between people who had nothing in common other than the shopping centre they all visited.

Community spread

This raises the question of essential workers, goods and services sustaining the ongoing community transmission that keeps the epidemic alive. The golden rule of infectious disease dynamics is that a small minority of people, venues or events account for most transmission. Focusing on these elements of ongoing transmission becomes even more important once a control response has been rolled out.

In relation to masks, I wince every time I see a well-meaning and hardworking Garda without a mask at a checkpoint speaking in sequence to the queue of dozens, hundreds or even thousands of motorists in a day.

Even with a minimum distancing of two metres, the cumulative risk of exposure for the poor Garda is higher than any of us would like, and if that well-intentioned essential worker does become infected he or she may become what is known as a “super-spreader” because of this high rate of even distant contact with others.

In another location I’m familiar with, there’s a food truck serving lots of popular takeaway snacks. While the staff and customers are protected from direct contact with each other by a Perspex shield, none of the staff wears masks, so I refuse to let our children order there.

Let’s not forget that the infamous Typhoid Mary, originally from Tyrone, infected so many people specifically because she was a cook who might be classified as an essential worker today.

I’d like to see masks made absolutely mandatory for anyone working in any essential service, especially anyone handing food, stacking shelves, moving goods, or working in any venue visited by members of the public.

Given that the virus can also persist on cardboard for up to a day, we don’t usually handle or open our mail until the day after delivery, and I’d be reassured to know mask use was compulsory at postal and delivery services.

When one thinks about it, there are many opportunities to close gaps in our ongoing response effort that could really accelerate the collapse of the epidemic. Instead of using masks to enable easing of restrictions, we could instead use them to enhance their impact and really crush the curve of the epidemic, ideally eliminating it within months.

Not simple

Of course, we need to address supply and availability issues but, as other countries have proven, that’s very doable. The best masks should indeed go to medical staff and other front-liners at greatest risk and with the greatest potential to pass the infection to many others. For the rest of us, much can be achieved with imperfect but nevertheless invaluable face coverings like the dampened cloth in the “Stay healthy!” video.

IMG-20200503-WA0000 Tanzanians wearing masks. Source: Professor Gerry Killeen

To begin with, there’s a repurposing of existing manufacturing capacity, as we’ve seen in a variety of clothing manufacturers across Ireland. As demonstrated here bhy our friends in Tanzania, where we just came from, and by our family in Brazil where my wife hails from, there’s also the DIY option and great “how to” instructions available on the internet.

‘Perfect is the enemy of the good’

In public health, our mantra is to never let the perfect get in the way of the good. It’s crucially important to get on with doing your best with whatever tools you already have rather than waste time waiting for something ideal.

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In the absence of better options, homemade masks, scarves and any other face-covering people can make practical use of having an invaluable role to play that is literally plain to see.

It’s now long overdue to heed the advice of our Chinese friends and get on with promoting the widespread use of masks, especially making sure they are compulsory in some shape or form among most of the personnel responsible for essential goods and services.

Professor Gerry Killeen is AXA Research Chair in Applied Pathogen Ecology at the School of Biological, Earth & Environmental Sciences, and Environmental Research Institute, University College Cork.

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Professor Gerry Killeen

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