The case for keeping your distance

As the restrictions start to lift and we all start to emerge from our COVID cocoons, a newly published study serves as a timely reminder to heed our social distancing rules.

The systematic review and meta-analysis which appeared in the Lancet confirms that maintaining a physical distance of at least a metre between individuals will significantly reduce the risk of contracting coronavirus, and if you make that distance at least two metres you are likely to reduce your risk even further.

“The findings of this systematic review … provide the best available evidence that current policies of at least 1m physical distancing are associated with a large reduction in infection, and distances of 2m might be more effective,” the study authors wrote.

You might have thought this was an already proven fact but the reality is there have been no randomised controlled trials on what is the optimum distance for avoiding person-to-person virus transmission, or at least coronavirus transmission. This is why the WHO funded this study.

The researchers sought out all the studies related to transmission of not only the SARS-CoV-2 virus but also the other betacoronaviruses that caused SARS and MERS. This included a large body of published work from China. In the end they analysed data from 172 observational studies from 16 countries and six continents.

Because the studies weren’t RCTs, the researchers were reluctant to put definite numbers about the degree of risk reduction conferred by social distancing. However, they were able to determine that a distance of at least one metre was more protective than a distance of less than a metre, and a distance of at least two metres was better again.

They also looked at other non-pharmacological protective measures, in particular face masks and eye protection. From their analysis it appears both measures help lower the risk of transmission.

“These data also suggest that wearing face masks protects people (both healthcare workers and the general public) against infection by these coronaviruses, and that eye protection could confer additional benefit,” they said.

In terms of the face masks, the study authors found that the N95 masks or similar offered greater protection than other masks, but once again the data was difficult to quantify.

But while the findings of this study will be heartening to health policy makers around the world who have been advocating such measures, the study authors make a point of saying social distancing, face masks and protective eyewear don’t provide the entire answer.

“None of these interventions afforded complete protection from infection, and their optimum role might need risk assessment and several contextual considerations,” the authors warned.

Nonetheless, the findings are an important reminder that we should continue to take these relatively simple, and now evidence-based measures to at least help avoid a re-emergence of COVID-19, which is what we all fear as the restrictions get relaxed.

Derek K Chu, Elie A Akl, Stephanie Duda, Karla Solo, Sally Yaacoub, Holger J Schünemann. Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and
COVID-19: a systematic review and meta-analysis. The Lancet. 2020, June 1; DOI: 10.1016/S0140-6736(20)31142-9

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