Catch up on science articles you may have missed from March and April 2020. Articles this month look at the science behind measures to contain Covid-19.
The British Medical Journal (BMJ) weigh up the evidence on the use of face masks during the Covid-19 pandemic. Trisha Greenhalgh and her co-authors argue that although the evidence on the efficacy of masks is “sparse and contested”, the high death toll of Covid-19 combined with the lack of treatment or vaccine mean that the wearing of face masks should be recommended.
The authors use the ‘precautionary principle’ as justification. The precautionary principle provides a structure for decision making when “scientific evidence about an environmental or human health hazard is uncertain and the stakes are high”. The authors conduct a brief review of the existing evidence for face masks, concluding that current evidence is limited and inconsistently applied. Arguments against the use of face masks are then considered. These include the risk that wearing a face mask may lead a person to touch their face more frequently to adjust the mask, and that the population will wear masks inconsistently and incorrectly. However, the authors argue that there is a “moral argument that the public should be given the opportunity to change their behaviour” and that the exceptional circumstances of the Covid-19 pandemic may mean that people are “highly motivated to learn techniques for most effective mask use”.
The article concludes by reaffirming the precautionary principle, stating that masks “could have a substantial impact on transmission with a relatively small impact on social and economic life”.
Read the full article: Trisha Greenhalgh et al, ‘Face masks for the public during the Covid-19 crisis’, British Medical Journal, 9 April 2020.
The Maths Behind Social Distancing
Writing for the University of Oxford’s science blog, Sarah Whitebloom examines the maths behind social distancing. Researchers at the university used the rule of three to illustrate how quickly Covid-19 can spread. If one person passes the viruses on to three people during one week, and during the subsequent week those three people each pass the virus onto another three people, then within six weeks 1,093 people will have been infected. If social distancing measures are introduced, and that initial person reduces their social contacts by a third, after six weeks only 127 people will have been infected. The researchers stress that social distancing was not required for previous strains of the virus, such as SARS, as individuals with these viruses displayed clearer patterns of symptoms. This meant the outbreak could be more easily controlled by finding and isolating symptomatic cases. With Covid-19, uncertainty about the wide spectrum of symptoms make social distancing much more important in containment efforts.
Read the full article: Sarah Whitebloom, ‘Social distancing works: here’s the maths‘, Oxford Science Blog, 6 April 2020.
Social Distancing – An Evolutionary Perspective
While some researchers have shown the maths behind social distancing, others have focused on the difficulties for people adapting to such behaviour. In this piece for the Conversation, researchers from Bangor University argue that the reasons many people find social distancing fundamentally unnatural can be found in evolution. Humans evolved from primates, a group distinguishable from others partly due to their high levels of social interaction. This tendency to live in groups, the authors argue, provided early humans with certain advantages. These included a better defence against potential predators, a higher number of care givers for infants, and more capacity to generate and retain knowledge. The development of language and culture in humans, as well as the division of labour, also relied heavily on social interaction. These factors mean that enforced social distancing feels highly unnatural for many people. However, the article concludes by making a distinction between physical and social distancing. Humans, the authors argue, have a talent for “adapting and innovating” in difficult circumstances. The advance of technology means that, while we may all be physically more distant from one another, in many ways we are socially more connected than ever before.
Read the full article: Isabelle Catherine Winder and Vivien Shaw, ‘Coronavirus: experts in evolution explain why social distancing feels so unnatural‘, The Conversation, 25 March 2020.