According to a new study released by British international medical research organisation Cochrane, wearing a face mask may make “little to no difference” in preventing the spread of respiratory viruses, including COVID.
Based on the research which was published on 30 January, and is an update of a Cochrane Review last published in 2020, researchers said they were left “uncertain whether wearing masks or N95/P2 respirators helps to slow the spread of respiratory viruses based on the studies we assessed”.
They added that hand hygiene programmes, however, “may help to slow the spread” of respiratory viruses. In addition, researchers were keen to stress the various limitations of the study and the need for further research around the effectiveness of interventions including face masks.
The research was carried out by a number of scientists and academics, including prominent British epidemiologist, Tom Jefferson, of the Cochrane Collaboration, and others who are part of Cochrane’s respiratory infections group – which conducts systematic reviews of the evidence and treatment for prevention of acute respiratory infections.
The study aimed to assess the effectiveness of physical interventions to interrupt or reduce the spread of acute respiratory viruses – which are viruses that infect the cells in your airways: nose, throat, and lungs. As outlined by the authors, these infections can cause serious problems and affect normal breathing. They can cause flu (influenza), severe acute respiratory syndrome (SARS), and COVID-19.
Those who are infected with a respiratory virus spread virus particles into the air whenever they cough or sneeze. Others can become injected if they come into contact with these virus particles in the air or on surfaces. Respiratory viruses can spread rapidly through a community, and as the authors point out, also through populations and countries (causing epidemics) and around the world (leading to pandemics).
The authors searched CENTRAL, PubMed, Embase, CINAHL, and two trials registers in October 2022, with backwards and forwards citation analysis on the new studies. The research included randomised controlled trials (RCTs) and cluster‐RCTs investigating physical interventions (screening at entry ports, isolation, quarantine, physical distancing, personal protection, hand hygiene, face masks, glasses, and gargling) to prevent respiratory virus transmission.
To collect the data, it used standard Cochrane methodological procedures. Breaking down the results, the authors explained that they included 11 new RCTs and cluster‐RCTs (610,872 participants) in the study.
This brought the total number of RCTs to 78. Six of the new trials were conducted during the COVID‐19 pandemic; two from Mexico, and one each from Denmark, Bangladesh, England, and Norway. Researchers identified four ongoing studies, of which one is completed, but unreported, evaluating masks concurrent with the COVID‐19 pandemic.
Researchers included 12 trials comparing medical/surgical masks versus no masks to prevent the spread of viral respiratory illnesses. Two trials were conducted with healthcare workers, while 10 were done in the community. They found that wearing masks in the community “probably makes little or no difference to the outcome of influenza‐like illness (ILI)/COVID‐19-like illness compared to not wearing masks”.
They added that: “Wearing masks in the community probably makes little or no difference to the outcome of laboratory‐confirmed influenza/SARS‐CoV‐2 compared to not wearing masks”. According to researchers, results using healthcare workers “made no difference” to the overall findings.
Researchers pointed out that during several studies, the discomfort associated with wearing medical/surgical masks was mentioned. When it came to hand hygiene, researchers used 19 trials to compare hand hygiene interventions with controls in settings including homes, schools, and childcare centres.
It found that hand hygiene measures may indeed be beneficial, pointing to an 11% relative reduction of respiratory illness.
Despite the results, researchers have stressed the limitations of the study in drawing firm conclusions. Factors including the high risk of bias in the trials, relatively low adherence to the chosen interventions, and a variation in how the outcomes were measured “hampers” drawing firm conclusions, the findings state.
Drawing attention to the limitations of the study, researchers said that the harms associated with physical interventions such as masking were under‐investigated, and that there is a need for further research to address the effectiveness of such interventions in multiple settings and populations. The impact of adherence on effectiveness should also be studied further, especially in those who are most at risk of acute respiratory illness.
Authors concluded that there “is uncertainty about the effects of face masks” – however they stressed that the limitations of the study and the uncertainty of the evidence means findings remain uncertain. However, they said that the pooled results “did not show a clear reduction in respiratory viral infection” with the use of face masks, adding that hand hygiene is “likely to moderately reduce” respiratory illnesses.
The publication of the new study comes as Health Minister Stephen Donnelly said at the start of January that plans to bring back mask-wearing are “under review” daily, prompted by an increase in cases of flu, Covid, and other respiratory viruses.
Speaking to Newstalk last month, he said the contentious issue of a mask mandate was not on the horizon, but would be assessed “on a daily and on a weekly basis”.
“The public health advice to Government, and to me at the moment, is not to move to mask mandates,” he told the programme.
“Obviously we will keep the situation under review on a daily and weekly basis,” he added.
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