Covid-19, masks and the precautionary principle

By Dr Mark Daniel Lopez

Scientific evidence on the efficacy and acceptability of masks in the prevention of respiratory infections during pandemics is scarce and contested. Now, an increasing number of countries are mandating the use of masks for the prevention of the spread of SARS-COV-2 [the virus that causes Covid-19], especially in the face a rising number of deaths across the globe and the gradual lifting of the lockdown restrictions.

Six weeks after the Chief Minister announced the lockdown the Government has began to “Unlock the Rock”, social media posts have flooded our news feeds with photos of a packed Main Street, busy with fellow Gibraltarians either exercising or getting some desperately needed fresh air, while others buy goods from shops that had previously been closed.

Throughout the Covid-19 campaign the Government and Public Health Gibraltar (PHG) have been reiterating to Catch it, Bin it, Kill it and in a recent press conference the CM asked that those who have hay fever sneeze into a tissue and throw it out especially because you might be suffering from Covid-19 and not know it. But yet there is no definitive implementation of public masks use.

The benefit of mass public masks usage in Gibraltar has been dismissed and indication of individual use not particularly clear. In a GBC interview the Director of Public Health told us that there was no added benefit of mask use, it created a sphere of avoidance around you and only serves to highlight your own internal anxieties. In late April, via Twitter, he said to use masks in “enclosed spaces (only)”.

The rationale for not implementing mass masking has been put down to lack of evidence, but policy makers shouldn’t misinterpret absence of evidence for evidence of absence.

This is why I suggest an approach to this issue by using the ‘Precautionary Principle’.

The Precautionary Principle is a strategy which allows policy makers to make interventions to deal with weakly understood causes of potential catastrophic or irreversible events. These principles provide a legal justification for acting even in the face of incomplete or currently un-evidenced scientific causation – for example, in the face of a deadly virus such as Covid-19 in an immune naïve population.

The rationale for the "Catch it, Bin it, Kill it" campaign is to limit aerosols during coughs or sneezes. The same rationale is championed by leading international public health organisations but instead with the use of face masks or face covers. The US Center for Disease Control and Prevention (CDC) has advocated the use of face masks in public during this current pandemic. The World Health Organisation (WHO), while not advocating the widespread use of masks, has acknowledged that there could be a place for face masks during pandemics as they offer a partial protective effect of limiting an aerosol, which could have a major influence on the transmission of respiratory viruses. The WHO is conducting ongoing research on this issue.

Most of the studies that measured the efficacy of masks in randomised trials failed to measure adherence of proper mask wearing and handling, and in one study, half the participants didn’t wear the masks most of the time. Unlike these studies, in the face of a serious pandemic, it is likely that adherence of proper mask use by the public would be higher than in studies looking at seasonal flu.

Moreover, studies where mask use for influenza showed no statistical significance could be due to the reproduction number being significantly lower than that of the reproduction number of unmitigated Covid-19. The higher the reproductive number, the higher the potential benefit of wearing masks could be, and possibly greater the likelihood of statistical significance. In other words, if they studied SARS-CoV-2 instead of influenza they could have found a statistical significance in the justification of mask use.

Furthermore, it is well documented that the viral shedding of SARS-CoV-2 occurs early in the course of the disease and models suggest that 40-80% of transmission events occur from people who are yet not showing any symptoms and that in controlled environments they can persist in the air for several hours and aerosols seem to be blocked by surgical masks in laboratory experiments.

More and more doctors are pleading for the use of masks in public, especially now that the restrictions are being slowly lifted and we return to ‘a new normal’. In the cases where masks are in short supply the CDC advises that everyone should wear a cloth face cover when they are out in public as this is supposed to help protect others if you are infected. In essence, catching the virus in your mask, is allowing you to then bin it and kill it.

Even if there is limited evidence, I am glad to see the recent suggestion by Together Gibraltar asking for mass masking in public and especially while undertaking indoor activities – an example of using precautionary principles. They also asked for the compulsory use of masks by healthcare professionals in the acute setting – where we cannot ignore the higher infection and mortality rates among frontline workers in countries where there is mask shortages compared to those better equipped and more consistently protected.

As further indirect evidence emerges (for example a study in Hong Kong comparing the rate of infection from Covid-19 before and after widely adopting masks) increasingly more countries are adopting the mass use of masks. Given the indirect findings, the seriousness of the outbreak and the “Unlocking The Rock”, there is a moral argument to implement public use of masks in line with the precautionary principle.

There could be an argument that masks can cause a false sense of security and non-compliance of other anti-contagion measures, like social distancing. To mitigate this I propose that there should be an immediate and strong campaign on how the public should effectively use masks. Gibraltar is a community of fast adaptation and as we saw in lockdown, a population with good compliance.

Unfortunately, Gibraltar is also a territory of very limited space and Main Street, as we have seen, can quickly get crowded. For these reasons I think we would be better off “Unlocking the Rock” with additional safety measures, including advocating the use of masks especially in confined or busy public spaces.

Dr Lopez is a Gibraltarian doctor in General Practice Speciality Training in Southampton, UK where he has trained in Southampton General Hospital Adults' A&E and Southampton Children's Hospital A&E. He is currently rotating through Acute Psychiatry. He undertook his foundation training in Gibraltar and was a Surgical Doctor for two years in St Bernard's Hospital. He has an interest in politics, public health and occupational medicine and plans to return to Gibraltar in 2022 after his training.