Existing limited evidence suggests that wearing face coverings to protect against COVID-19 does not lead to a false sense of security and is unlikely to increase the risk of infection through wearers foregoing other behaviours such as good hand hygiene, say researchers from the University of Cambridge and King’s College London.
Writing in BMJ Analysis, the authors researchers that the concept of ‘risk compensation’ is itself the greater threat to public health as it may discourage policymakers from implementing potentially effective measures, such as wearing face coverings.
Wearing face coverings, particularly in shared indoor spaces, is now mandated or recommended in more than 160 countries to reduce transmission of SARS-CoV-2, the virus that causes COVID-19. Worn correctly, face coverings can reduce transmission of the virus as part of a set of protective measures, including maintaining physical distance from others and good hand hygiene.
While it is not clear how much of an effect face coverings have, scientists have urged policymakers to encourage the wearing of face coverings because the risks are minimal while the potential impact is important in the context of the COVID-19 pandemic.
However, early in the pandemic, the World Health Organization warned that wearing face coverings could “create a false sense of security that can lead to neglecting other essential measures such as hand hygiene practices”. This type of behaviour is known as ‘risk compensation’.
A team led by Professor Dame Theresa Marteau at the Behaviour and Health Research Unit, University of Cambridge, has examined the evidence for risk compensation to see whether concerns might be justified in the context of face coverings to reduce transmission of SARS-CoV-2.
The idea behind risk compensation is that people have a target level of risk they are comfortable with and they adjust their behaviour to maintain that level risk. At an individual level, risk compensation is commonplace: for example, people run for longer to offset an eagerly anticipated indulgent meal and a cyclist may wear a helmet to cycle at speed.
At a population level, evidence for risk compensation is less clear. A commonly-cited example is the mandated wearing of bike helmets purportedly leading to an increase in the number of bike injuries and fatalities. Another often-cited example is the introduction of HIV pre-exposure prophylaxis (PrEP) and HPV vaccination purportedly leading to an increase in unprotected sex.
Professor Marteau and colleagues say the results of the most recent systematic reviews – a technique that involves examining all available evidence on a topic – do not justify the concerns of risk compensation for either of these examples. In fact, for HPV vaccination, the opposite effect was found: those who were vaccinated were less likely to engage in unprotected sexual behaviour as measured by rates of sexually transmitted infection.
At least 22 systematic reviews have assessed the effect of wearing a mask on transmission of respiratory virus infections. These include six experimental studies, involving over 2,000 households in total – conducted in community settings that also measured hand hygiene. While none of the studies was designed to assess risk compensation or looked at social distancing, their results suggest that wearing masks does not reduce the frequency of hand washing or hand sanitising. In fact, in two studies, self-reported rates of hand washing were higher in the groups allocated to wearing masks.
The team also found three observational studies that showed people tended to move away from those wearing a mask, suggesting that face coverings do not adversely affect physical distancing at least by those surrounding the wearer. However, they say that as none of these studies have been peer-reviewed, they should be treated with caution.
“The concept of risk compensation, rather than risk compensation itself, seems the greater threat to public health through delaying potentially effective interventions that can help prevent the spread of disease,” said Professor Marteau.
“Many public health bodies are coming to the conclusion that wearing a face covering might help reduce the spread of SARS-CoV-2, and the limited evidence available suggests their use doesn’t have a negative effect on hand hygiene,” added co-author Dr James Rubin from the Department of Psychological Medicine, King’s College London.
In their article, the team argue that it is time to lay risk compensation theory to rest. Professor Barry Pless from McGill University, Montreal, Canada, once described it as “a dead horse that no longer needs to be beaten.” The authors go further, saying “this dead horse now needs burying to try to prevent the continued threat it poses to public health, from by slowing the adoption of more effective interventions”.
The researchers are supported by the National Institute for Health Research.
Reference
Mantzari, E et al. Is risk compensation threatening public health in the covid-19 pandemic? BMJ Analysis; 27 July 2020: DOI: 10.1136/bmj.m2913
About the University of Cambridge
The mission of the University of Cambridge is to contribute to society through the pursuit of education, learning and research at the highest international levels of excellence. To date, 109 affiliates of the University have won the Nobel Prize.
Founded in 1209, the University comprises 31 autonomous Colleges and 150 departments, faculties and institutions. Cambridge is a global university. Its 19,000 student body includes 3,700 international students from 120 countries. Cambridge researchers collaborate with colleagues worldwide, and the University has established larger-scale partnerships in Asia, Africa and America.
The University sits at the heart of the ‘Cambridge cluster’, which employs more than 61,000 people and has in excess of £15 billion in turnover generated annually by the 5,000 knowledge-intensive firms in and around the city. The city publishes 316 patents per 100,000 residents.
About King’s College London and the Institute of Psychiatry, Psychology & Neuroscience
King’s College London is one of the top 10 UK universities in the world (QS World University Rankings, 2020) and among the oldest in England. King’s has more than 31,000 students (including more than 12,800 postgraduates) from some 150 countries worldwide, and some 8,500 staff.
The Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London is the premier centre for mental health and related neurosciences research in Europe. It produces more highly cited publications in psychiatry and mental health than any other university in the world (Scopus, 2016), with 21 of the most highly cited scientists in this field. World-leading research from the IoPPN has made, and continues to make, an impact on how we understand, prevent and treat mental illness and other conditions that affect the brain.
About the National Institute for Health Research
The National Institute for Health Research (NIHR) is the nation’s largest funder of health and care research. The NIHR:
- Funds, supports and delivers high quality research that benefits the NHS, public health and social care
- Engages and involves patients, carers and the public in order to improve the reach, quality and impact of research
- Attracts, trains and supports the best researchers to tackle the complex health and care challenges of the future
- Invests in world-class infrastructure and a skilled delivery workforce to translate discoveries into improved treatments and services
- Partners with other public funders, charities and industry to maximise the value of research to patients and the economy
The NIHR was established in 2006 to improve the health and wealth of the nation through research, and is funded by the Department of Health and Social Care. In addition to its national role, the NIHR supports applied health research for the direct and primary benefit of people in low- and middle-income countries, using UK aid from the UK government.
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