HAVE existing social distancing measures succeeded in suppressing Covid-19 to an extent that there is now scope to relax them further?

That is the question facing Nicola Sturgeon and colleagues today as we weigh up a transition into Phase Two of the route-map out of lockdown.

If so, pubs and restaurants with outdoor spaces will be allowed to re-open them to customers. Children’s playgrounds, non-food shops and professional sport can return.  Public transport services will increase – although travel during rush hour would be discouraged – and Scots will be allowed to meet with another household indoors again for the first time since March, and hold larger gatherings with friends and family outdoors.  Current statistics appear to indicate that the prevalence of the virus has reduced significantly since mid-May.

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In the week ending May 18, 967 positive Covid cases were detected through NHS labs. Over successive weeks that number has fallen steadily, from 562, to 262, 221, and in the week ending June 15 was down to just 145 – a decline of 85 per cent in four weeks.  Results from regional drive-thru and mobile testing centres have only been included since Monday, and the number of positives from home-testing kits are still missing from the official statistics.  However, initial data from the Test & Protect regime, which does include drive-thru results, suggests they are following a similar curve, with 477 cases picked up between May 28 and June 14 to the 515 detected in NHS labs.

The number of confirmed Covid cases in hospital has also halved, from 1,145 on May 11 to 578 by June 15; among intensive care patients the decline has been even more dramatic – from 72 to 12.  In care homes, the number of “suspected” cases recorded among residents is down nearly 77%, from 623 in the week ending May 18 to 146 in the week to June 15.  Scotland’s “R number” has dropped for the first time in two months, to a range of 0.6-0.8 compared to 0.7-0.9 previously, although the Government’s scientific advisors cautioned that their modelling could not yet take full account of the impact of Phase One relaxations.

At present, the trajectory appears to be downwards, but with that is coming increased pressure to drop the two-metre physical distancing rule in favour of a less stringent one-metre gap which has the backing of the World Health Organisation.  Pub, hotel and restaurant owners have argued that two-metre physical distancing requirements would torpedo what remains of their businesses. For restaurants, it is said to be the difference between being able to operate at 70% capacity or an untenable 30%.

Like so much else in Covid-19 “the science” does not offer us any black and white answers to the problem, except that – as you might expect – a distance of two metres is better for infection control than one metre.  The dilemma is how much of a difference it makes, and whether that is worth it when balanced against the economic hardship it brings: mass unemployment and loss of livelihoods have their own serious public health fallout.  The most comprehensive study to date was published this month in the Lancet. It analysed nine existing studies which compared the benefits of one and two metre distancing for cutting the transmission of three coronaviruses: Covid-19, SARS, and MERS.  

They found that standing within one metre of an infected individual carried a 12.8% risk of becoming infected, compared to 2.6% when standing more than a metre away. 

The findings were similar for all three viruses, although the researchers noted that only six of the 38 studies they examined related specifically to Covid, and none were randomised control trials – the gold-standard for research. 

Although they said “a strong association was found of proximity of the exposed individual with the risk of infection”, they described the certainty of the evidence on physical distancing as “moderate”.  In summary, they concluded that it provides “the best available evidence that current policies of at least one-metre physical distancing are associated with a large reduction in infection, and distances of two metres might be more effective”.

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Many of the countries with the best track record against Covid – Singapore, Greece, South Korea – recommend distancing of 1-1.5 metres. But their infection rates are already substantially lower than the UK. 

Adopting it here would increase requirements for face masks and carry implications for contact tracing, which currently requires anyone who has spent 15 minutes within two metres of someone later found to be infected to self-isolate as a precaution.

At one metre, that requirement would kick in at around two minutes.  If the hospitality sector is to re-open as planned from July 15, especially with any reduction in physical distancing, evidence of further substantial reductions in virus transmission will probably be required.