Coronavirus: Is social distancing safe at less than two metres?
The UAE is among nations adopting the most demanding standard of two metres, double the distance recommended by the World Health Organisation
As more countries move out of lockdown, pressure is mounting to address one of the key means to combat Covid-19: social distancing.
Restrictions on how close people can be to one another are increasingly seen as the biggest barrier to returning to normal life. Places of worship, schools, offices, cinemas, shopping malls have been hit by the need to keep a minimum distance.
There is some concern the measure hampers efforts to revive national economies.
What is the current policy on social distancing?
The UAE is among nations adopting the most demanding social distancing standard of two metres, double the standard recommended by the World Health Organisation.
This has played a part in the country's success in controlling Covid-19, with a per capita mortality rate 20 times below that of the UK and Spain.
But it is unlikely to have been the decisive factor: both the UK and Spain have adopted the two-metre standard.
Ironically, some countries praised for their success in tackling the virus have adopted less stringent standards. The guidance is 1.5 metre in Australia, 1.4 metre in South Korea, and just one metre in Singapore.
Social distancing certainly helps but is only part of an effective strategy.
So what good does it do?
There are no scientifically robust studies of how distancing affects the risk of infection in real life. The two-metre figure has its origins in experiments performed in the 1930s into the spread of droplets from coughs and sneezes.
Field studies of infection rates provide some insight in different settings such as hospitals.
The Lancet this month published the most comprehensive review of the evidence specific to the coronaviruses that cause the Covid-19, Sars and Mers epidemics. Based on more than 30 studies from 10 countries, the results suggest that a one-metre distance standard cuts the infection risk more than four-fold, to just 3 per cent.
The researchers acknowledged that many studies fail to report the duration and severity of exposure or whether masks were used, casting doubt on the figures.
Would easing the standard make a big difference?
According to the study, the two-metre distance standard leads to an infection risk half that of one metre, at around 1.5 per cent. The decision to ease the restrictions thus depends on whether the extra risk is acceptable.
Many experts do not doubt the benefits.
Prof David Paton, an economist at the University of Nottingham Business School, told the BBC that from an economic point of view "moving from two metre to one metre is probably the most important and significant measure in terms of getting the economy back on its feet again”.
The move would make queues half as long, and increase the number of people who can gather in a given area.
But the impact is less impressive than often claimed.
While halving the distance shrinks the “exclusion area” four-fold, such large increases in capacity only applies to empty spaces. Venues such as cinemas, theatres and stadiums benefit much less because of the constraint imposed by fixed seating plans.
What is the best way forward?
The principal concern of many countries remains the threat of a second wave of Covid-19. This could still overwhelm health services and would force a return to lockdowns bringing any economic revival to a halt.
For that reason, many governments will be reluctant to ease distancing standards without stepping up other countermeasures like mask wearing and testing, tracing and isolating programmes.
Robert Matthews is visiting professor of science at Aston University, Birmingham, UK
Updated: June 13, 2020 02:59 PM