Masks and the coronavirus
The World Health Organization (WHO) has changed its position on the wearing of face masks, suggesting they should be worn in situations where social distancing is not possible to help stop the spread of coronavirus.
Since the start of the COVID-19 pandemic, new evidence has demonstrated that masks may reduce the spread of potentially infectious droplets. Some countries already recommend or are even making it law that face coverings be worn in public.
The WHO had previously stated there was not enough solid science suggesting that healthy people should wear masks.
At the same time, the WHO stressed that face masks were just one of a range of tools that could be used to reduce the risk of transmission – and that they should not give people a false sense of protection.
There is also emerging research that the coronavirus may also be highly infectious in the days before the illness becomes symptomatic and occasionally a person will contract the virus & have no symptoms.
Thus, when social distancing is not possible, such as any public areas, faces should be covered with masks to avoid passing on the infection.
The director-general of the WHO Dr Tedros Adhanom Ghebreyesus recently stated: “in light of evolving evidence, the WHO advises that governments should encourage the general public to wear masks where there is a widespread transmission and physical distancing is difficult, such as on public transport, in shops or in other confined or crowded environments”.
The WHO has always advised that medical face masks should be worn if you are already ill with a respiratory illness, have known predisposing factors to the more serious form of COVID-19, or a carer for anyone in this situation. Now it is being recommended that those aged over-60, especially with underlying health risks, should wear medical grade face masks in areas where there is community transmission. For other people without known medical issues or in the sick, elderly group, any form of mask will suffice.
Globally, there have been 6.7 million confirmed coronavirus cases and nearly 400,000 deaths since the outbreak began late last year.
There are conflicting reports from a number of sources around the benefits of masks in regard to protection from developing COVID-19. One study, published in Nature Medicine from the University of Maryland used a particular breath capturing machine to study this very issue. The researcher, Dr Don Milton, demonstrated in 2013 that surgical masks may reduce the transmission of influenza. Dr Milton suggests that not just coughing & sneezing but also tiny, aerosolised droplets through normal breathing can also transmit the virus. Any form of mask can certainly prevent this from occurring.
This study examined 246 people with suspected respiratory infections and showed that surgical masks reduced detectable virus in respiratory droplets containing the common cold coronavirus and influenza. Interestingly masks did not prevent the spread of rhinoviruses, the most common virus detected when a person experiences the common cold. Thus, the conclusion of this study was that the use of surgical masks did reduce the spread of respiratory infections, such as COVID-19 and influenza. There appears to be even greater protection from the use of N95 type masks.
But, in another study recently published in the Annals of Internal Medicine but in only four patients with proven COVID-19, the wearing of surgical or cotton masks appeared to have no effect on the spread of the virus when these patients were asked to cough. The masks were swabbed on the inside, the outside, and on a nearby Petrie dish with the virus being found on all surfaces. This study, however, did not look at whether these masks prevented the spread of the virus through normal breathing, which was suggested in the first study. It was also in only four very sick patients & really cannot be extrapolated to large groups of healthier people with lesser viral loads i.e. most of us going about our daily business & otherwise feeling well.
It was also found in another study that coughing, breathing, or even talking can spread the virus 4 metres, even more than our current social distancing guidelines.
The World Health Organization (WHO) commissioned a meta-analysis of 20,000 research papers finally reviewing 44 comparative studies of the protective benefits of physical distancing, wearing face masks, or eye protection.
These studies examined the benefits of these varying techniques in regard to COVID-19, SARS & MERS. There were no differences in the effectiveness of distancing, face masks, and eye protection in responses to the three coronaviruses.
- Social distancing works
There is good evidence that maintaining a minimum distance of 1 meter from other people is likely to reduce the spread of the virus. In 38 studies that included information about distancing, infection rates overall were reduced to 2.6% when maintaining a distance of more than 1 meter from a person with the infection. Amongst studies in which distancing was less than 1 meter, the infection rate was 12.8%. These studies also suggested that increasing the distance to 2 meters was likely to have an even greater effect. It is suggested that 2 meters should be adopted universally.
It appears that the virus is transmitted through droplets expelled from a person’s throat or nose when they cough or sneeze. These droplets do not remain airborne for very long, explaining why distances of at least 1 meter significantly reduce transmission.
It is also suggested that aerosol survives as small particles being expelled as a person coughs and sneezes. Aerosol-based particles potentially remain airborne for longer and thus infect a person at a greater distance.
- Face masks
Face and eye masks are designed to stop the spread of the virus, either by containing the amount a person expels or decreasing contact with mouth or eyes and, thus, the respiratory system.
The studies suggested that both face and eye masks significantly reduced transmission of the virus for health care workers and other people with significant social contact.
The odds of developing coronavirus infection were reduced by 78% when wearing any mask, compared with the odds of infection when not wearing a mask. When using masks that conform to the N95 standard or equivalent, this increased to 96%.
In conclusion, on the balance of evidence, it is better to wear a mask in public. It will probably reduce the spread of the virus and thus reduce our risk of catching the virus. Also, it is probably best to wear the more effective N95 style masks. But, any mask is better than no mask.
Our current social distancing, isolation & restrictions have clearly worked in Australia where we are, in reality, the poster child for coronavirus control. Wearing masks is probably yet another aspect of this excellent pandemic control-a tribute to all Australians.
Dr Ross Walker