Face Masks for COVID: An Obituary?
The management of the COVID-19 pandemic by national governments, public health departments and international agencies has often been marked by claims to be following ‘the science’ – and attempts to brand any critical discussion of that science as ‘misinformation’. It is a basic tenet of the sociology of deviance that the labeling of an act as ‘deviant’ tells us as much about the labeler as the labeled. Nowhere is this more true than in the controversy over the use of face masks as a means of preventing the transmission of the SARS-Cov-2 virus between people in community settings.
At the very beginning of the pandemic, the official view, based on the science of the time, was that masks had no value outside healthcare settings. A major source for this was the Cochrane Review of evidence for physical interventions to interrupt or reduce the spread of respiratory viruses. The first edition was published in 2007, with updates in 2009, 2010 and 2011. A further, major, update was in press at the beginning of the pandemic and published on April 1, 2020. Cochrane Reviews are the gold standard for evidence-based medicine. They are published only after an exhaustive, and exhausting, process of peer review, with full transparency about their strategies for identifying studies to include and the material interests of their authors. This is as good as it gets, and the reports are rightly treated as definitive summaries of the state of biomedical knowledge at the time of publication.
Cochrane Reviews give the greatest weight to randomized controlled trials (RCTs) as evidence. These have the smallest risk of bias of any epidemiological method. A population is randomly assigned to a group that received an intervention (e.g. masks) and one that does not (control). In principle, the intervention is the only difference between the groups, eliminating other factors that might confuse the picture. In practice, this is difficult to achieve. The Cochrane Reviews deal with that problem by aggregating available RCTs in a meta-analysis. By pooling the results, it is likely that any biases that have crept in will cancel each other out and users can have more confidence in the result.
The 2020 Review was based on nine studies, mostly of influenza or influenza-like illness (ILI – people who had symptoms similar to flu but not confirmed by lab testing). Most of these studies were relatively small: they included an aggregate total of 3,507 people. The authors note various other problems that compromised the quality of the evidence. They concluded that it was ‘uncertain’ whether cloth or surgical face masks helped to slow the spread of respiratory viruses.
This work informed the starting position of the World Health Organization and many public health leaders with experience in the field. Skepticism about the value of masks was not misinformation at that time. However, this was reversed for reasons that have yet to be fully understood. Part of the story seems to be a claim that because COVID was a novel virus, all previous research on respiratory viral transmission should be disregarded. Part seems to relate to the simplistic Orientalism that I discussed in a previous post. Part seems to be attributable to the desire of political leaders to be seen to be ‘doing something’. Some part is probably also played by the encroachment of the parallel ‘epidemic of fear’ into the scientific community.
The full story will probably have to await the attention of historians but the consequences were to label anyone who criticized masking as a peddler of disinformation. Serious questions about the legitimacy of overt state intervention, through law, or covert state intervention, through ‘nudging,’ to promote a policy based on ‘uncertain’ evidence were dismissed as fringe libertarianism.
A further updated review has just been published, after a lengthy peer review and editorial process. The 2023 update includes the results of 12 trials, now covering 276,917 participants. The quality of evidence has been upgraded from low to moderate and the authors now conclude that there is ‘probably little to no benefit’ from cloth or surgical face masks in the community. They also considered RCTs comparing cloth or surgical masks with N95/P2 masks. The evidence here was weaker but suggested that these made little or no difference to transmission. The team regret the absence of funding for other trials, which might have permitted a stronger conclusion. In this, they are reiterating a call that they, and others, have been making since the summer of 2020 and which has consistently been ignored by those in a position to fund such work.
The review did not cover studies published after October 1, 2022. However, the large trial in Guinea-Bissau has now been published as a pre-print. This study, which has yet to pass peer review, involved 39,754 people. However, its validity was weakened by the low levels of compliance with cloth mask-wearing and the introduction of a government mask mandate. Nevertheless, its results are broadly consistent with those of the other studies considered in the Cochrane Review. It did not find any statistically significant difference between the mask-wearing group and the control group. At the very least, it does not challenge the conclusions of the Cochrane Group’s meta-analysis by finding a strong discrepant effect.
Taken as a whole, the Cochrane Review process should nail three myths. First, that the science did not suggest in spring 2020 that face masks were unlikely to make much difference to the course of the pandemic. This was the settled position, against which advocates for the intervention should have been expected to produce evidence, in accord with the precautionary principle.
Second, that the only thing wrong was the choice of cloth or surgical masks: if N95/P2 masks had been worn from the start, the outcome would have been no different.
Third, that all skepticism about mask-wearing resulted from a prior ideological commitment against state action rather than an expectation that ‘the science’ would hold itself to the standards that it had claimed to abide by for a generation. Dismissing criticism as disinformation, rather than as loyal opposition intended to improve policy and governance, takes us back to 17th-century theories of sovereign power and the right of those in government to impose tests of belief as a condition of participation in public life.
If RCTs have failed to provide the ‘right answer’ to the search for evidence to justify mask mandates or nudges, their advocates have looked in two other directions. Some social scientists have argued that they should be worn as a signal of emergency, of caring for those who feel themselves at exceptional risk from infection. Some scientific leaders have pointed to the mechanistic evidence from laboratory studies and modeling in physics and engineering. Both of these are weak arguments as I shall show in a future post. It is time to start writing the obituaries for a failed policy.