There is debate as to whether the UK should relax its 2 metre social distancing rules in line with the WHO recommendation to stay at least 1 metre apart so that certain businesses and the hospitality industry have a better chance of recovery.

The latest research has brought together evidence from 32 studies of over 10,000 people during pandemics of COVID-19, SARS and MERS. It found that when these people were in contact with someone with the infection, the risk of them catching it reduced from 12.8% when they stayed less than 1 metre apart to 2.6% when they stayed at least 1 metre apart. When this increased to 2 metres, the risk reduced to 1.3%.

There are no easy answers in how to ease lockdown while preventing a second peak. Studies such as this are vital in helping to inform these complex decisions.

Where did the story come from?

The media have reported on a systematic review published in The Lancet funded by the WHO.

The methods of the review were rigorous, but the findings are limited by being based on observational studies, which cannot rule other behaviours (like how often people washed their hands) impacting results. However, this is the best evidence currently available.

What is the basis for the claim?

The systematic review included 172 observational studies looking at the risk of transmission of SARS-CoV-2 and other similar respiratory coronaviruses between people with a known infection and those close to them (members of their household, caregivers, or healthcare workers) according to physical distance and use of face masks and protective eyewear.

The main results on distancing came from pooling the results of 29 of these studies (10,736 participants).

It found that the risk of transmission is 82% lower if people stay at least 1 metre apart compared to getting closer (adjusted odds ratio 0.18). This would mean the estimated actual risk of catching the virus would reduce from 12.8% to 2.6%. For every further metre apart, the risk was halved.

A separate study has looked at how the virus could be transmitted through droplets in the air from coughing. This modelling study found that droplets from a mild cough would not carry to 2 metres when there is no wind. However, with wind speeds of between 2.5mph to 8.5mph, they could spread up to 6 metres.

Six metre social distancing is clearly not an option, but this study does lend weight to keeping the 2-metre distancing rule.

What do trusted sources say?

The UK government advises that people should stay 2 metres apart from anyone outside of their household. The US Centers for Disease Control and Prevention (CDC) advice is similar, suggesting a 6 foot distance (about 1.8 metres). The WHO recommends staying at least 1 metre apart.

Analysis by EIU Healthcare, supported by Reckitt Benckiser

 

Citation and funding statement

  1. Chu DK, Akl EA, Duda S et al. 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. June 01 2020. DOI: https://doi.org/10.1016/S0140-6736(20)31142-9
    Funding: World Health Organization (WHO)

Reading list

  1. Dbouk T, Drikakis D. On coughing and airborne droplet transmission to humans. Physics of Fluids. 32, 053310 (2020). Published Online 19 May 2020.
  2. UK. Guidance: Staying alert and safe (social distancing). Updated 31 May 2020.
  3. US CDC. Social distancing. Last reviewed 6 May 2020.
  4. World Health Organization. Coronavirus disease (COVID-19) advice for the public. April 29 2020. Accessed 2nd June 2020.