Nobel prize-winning virologist Harold Varmus, Nobel prize-winning economist Bengt Holmström, the editors-in-chief of The Lancet and Nature, and more than 100 of the world’s top scientists signed an open letter that states that “fabric mask use in public places could be amongst the most powerful tools to stop the community spread of COVID-19”.
Masks could be the difference between success and failure in controlling the pandemic and saving the economy. Many papers, including those based on mathematical and computer models, global studies, and analysis of US states, estimate that if most people wear a mask with other simple measures like physical distancing, COVID-19 transmission can be greatly curtailed, or even halted. Goldman Sachs estimates the value of a mask mandate in the US would prevent a GDP loss of $US1 trillion.
The government currently only recommends mask use for those with symptoms. But this misunderstands how the virus can spread. Masks in the community are primarily for “source control” – that is, sick people wearing masks to avoid them infecting others. Nearly half of infections come from people who don’t know they are sick. Infectiousness is greatest before symptoms even appear.
The use of masks for source control is very different to the use of masks to protect the wearer, which is known as “PPE” (personal protective equipment). The vast majority of research has focused on PPE, and doctors’ training in Australia largely focuses on PPE, not source control. Therefore, a lot of older science, and medical intuition, is based on an “inside out” view of the problem. Whereas effective PPE requires specialised masks, simple cloth masks are likely to be effective for source control. Even a simple piece of cotton blocks 99 per cent of the speech droplets that are believed to spread the virus.
Nearly half of infections come from people who don’t know they are sick. Infectiousness is greatest before symptoms even appear.
Wearing a mask does not mean you mustn’t physically distance. The virus can spread by coughing or even talking, can travel for more than three metres and stay in the air for hours if there is poor ventilation. The further you distance from others, the greater you are protected. Keeping a metre apart reduces the risk of catching the virus by about 80 per cent, and for every added metre you stay apart, the protection against catching the virus increases. But when indoors, keeping three metres apart often isn’t practical.
The idea that widespread wearing of masks means people feel too secure and will ignore other important measures is the same argument that has been made in the past for seatbelts, motorbike helmets and skiing helmets. The arguments haven’t held up.
The Australian government guidance is out of date, with incorrect claims, and mirrors old guidance now abandoned around the world. Masks may also make other precautions more effective. For example, it appears that masks cause distancing to increase, not decrease.
In the fight against COVID-19, we should promote all infection control measures together, and not pit one against another. For instance, mask use means your germs travel less distance. The combination of masks and distancing is more effective than either one alone.
Australian infectious disease expert Raina MacIntyre notes that “there is more evidence supporting face mask use in the community than hand hygiene including in randomised controlled trials which compare both interventions directly, so it is inconsistent to advocate hand hygiene as a sound principle but not masks”.
Some may have concerns that recommending or requiring mask use may cause a run on medical masks, which are in short supply. However, this concern has not been borne out in practice. If you go anywhere that requires masks, such as San Francisco, New York, Israel or Germany, and take a look around, you will see that nearly everyone is wearing cloth masks, not medical masks. The US Surgeon General showed how to make one in 40 seconds from a handkerchief. Mask requirements do not take away critical protective equipment from doctors. Instead, they result in fewer people requiring hospitalisation.
Australia is a country that is rightly proud of its heritage of exceptional scientific and medical achievements. Australia’s rapid response to COVID-19, with effective lockdown and quarantine, has made it the envy of much of the world. Now is not the time to throw that good work away, when a strong response is most needed. It’s time to follow the lead of Melbourne’s hospitals, and ensure that in Australia masks are used in all public enclosed spaces and anywhere that there could be any community transmission.
Jeremy Howard is an Australian currently working as a distinguished research scientist at the University of San Francisco. Nick Talley is a Laureate Professor at the University of Newcastle, and editor-in-chief of the Medical Journal of Australia.
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