Reducing physical distancing advice from 2 metres to 1 metre could double the risk of coronavirus infection, according to the most comprehensive study to date. The research, commissioned and part-funded by the World Health Organisation (WHO), also concludes respirators rather than less protective surgical masks should be the ‘minimum’ requirement for health care work.

The study, published in the Lancet, comes in the week after the Prime Minister Boris Johnson said he hoped to “be able to reduce that [2-metre] distance” as part of the government’s plan to ‘ease’ the lockdown. The Lancet meta-analysis of 172 observational studies across Covid-19 but also – predominately – Sars and Mers, highlights the potential consequences of a change. It found that keeping a distance of more than 1 metre from other people reduced the risk of infection or transmission to 2.6 per cent, but this risk halved at 2 metres. The results make it clear that the WHO should recommend that essential workers like nurses and emergency responders wear respirators not just surgical masks.

David Michaels, a professor at George Washington University who headed the US safety regulator OSHA through the Obama administration, noted: “Reliance on surgical masks has no doubt led to many workers being infected,” adding that other workers like meatpackers also needed the higher level of protection. Current WHO guidelines do not recommend respirators for all health care workers caring for infected patients.