Coronavirus transmission is still too high to relax the social distancing two-metre rule, a government scientific advisor has said, amid mounting pressure to scrap it.
Professor Catherine Noakes, who sits on the Scientific Advisory Group for Emergencies (Sage), rebutted any claims that relaxing the two-metre rule is safe at this time.
An estimated 8,000 people are still being infected every day, but only a fraction - around 1,300 - are formally diagnosed.
Other countries have adopted a one-metre rule. A major study showed this doubles the risk of being infected, but the risk is still only 2.6 per cent.
Prime Minister Boris Johnson decided to keep the two-metre rule in place this week after asking scientists to review the evidence.
Professor Noakes said you could catch the coronavirus even if someone is standing four metres away in a poorly ventilated room.
It dashes hopes that pubs, bars and restaurants will safely be able to open in the near future, which is likely to see a number go bust.
Experts have pleaded with the PM to change his stance in order to protect businesses and the livelihoods of those who work there.
Professor Catherine Noakes, who sits on the Scientific Advisory Group for Emergencies (Sage), rebutted any claims that relaxing the two-metre rule is safe at this time. A major study showed one metre social distancing doubles the risk of being infected, but the risk is still only 2.6 per cent (pictured)
Catherine Noakes, an expert on airborne infection at University of Leeds, told The Times: 'There are too many cases in the community for us to consider going below two metres.'
'There is transmission happening already, when we've been applying the [two-metre] distancing. If we reduce it, essentially, you double the risk.
'Where you have a poorly-ventilated room and someone is four metres away - if there's a high viral shedder in that room, that could cause an infection.'
What is the science behind two-metre social distancing rule?
The World Health Organization (WHO) recommends a one metre distance between two people from separate households.
The reason for this, as stated on its website, is that: 'When someone coughs, sneezes, or speaks they spray small liquid droplets from their nose or mouth which may contain virus. If you are too close, you can breathe in the droplets, including the COVID-19 virus if the person has the disease.'
But other countries have taken advice from their own health experts and social distancing varies from two metres (in the UK) down to one metre (in France)
The two metre rule can be traced back to research in the 1930s that showed droplets of liquid from coughs or sneezes would land within a one-two metre range.
Social distancing varies between different countries:
TWO METRES: UK, Switzerland, US, Spain, Italy
1.5 METRES: Germany, Poland, Netherlands
ONE METRE: Austria, Norway, Sweden, Finland
SO, WHAT HAVE THE STUDIES SHOWN?
Number 10's chief scientific adviser - Sir Patrick Vallance - has said that the one metre rule is up to 30 times more risky than the two metre rule.
He told MPs earlier this month the risk of spending a minute next to a Covid-19 patient for two minutes was 'about the same' as being within a metre of a Covid-19 case for six seconds.
The latest evidence, published in The Lancet, found there was roughly a 2.6 per cent chance of catching the virus when one metre from a Covid patient. But doubling the gap cut the risk to only 1.3 per cent.
One of the top scientific advisers to the British Government said the two metre social distancing rule is based on 'very fragile' evidence.
Professor Robert Dingwall, a member of Nervtag, referred to it as a 'rule of thumb' rather than a scientifically proven measure.
Other experts have said the distance may be a non-scientific estimate that just caught on in countries around the world.
IS TWO METRES ENOUGH?
The UK's coronavirus social distancing limit is four times too short and the gap should be 26 feet, said experts at the Massachusetts Institute of Technology in March.
They found viral droplets expelled in coughs and sneezes can travel in a moist, warm atmosphere at speeds of between 33 and 100ft per second.
This creates a cloud in the atmosphere that can span approximately 23ft to 27ft (seven metres to eight metres) to neighbouring people, the team said.
Another study by scientists in Cyprus, published a fortnight ago, added to the evidence when it found the two-metre rule may not be far enough.
Researchers found even in winds of two miles per hour (mph) - the speed needed for smoke to drift - saliva can travel 18 feet in just five seconds.
And scientists from the universities of California Santa Barbara and Stanford last week said the two metre rule may have to be trebled when winter strikes.
They found droplets that carry SARS-CoV-2 - the coronavirus that causes Covid-19 - can travel up to 20feet (six metres) in cold and humid areas.
Professor Noakes referred to a recent major study by the World Health Organisation which looked at the risk of transmission depending on social distancing lenths.
It found that 'one metre reduces your risk and two metres halves it again'.
There was roughly a 1.3 per cent chance of contracting the virus when two metres from an infected patient.
One-metre increased the odds to 2.6 per cent - which is still very low, but double the risk of one metre.
'That really is showing two metres is a good distance,' Professor Noakes said.
MPs have called for the distance to be loosened in line with other countries such as Germany, to save jobs and allow more businesses to reopen.
If pubs, theatres and other hospitality venues have to abide by the two-metre rule, it would severely restrict how many could enter.
Senior MPs say tens of thousands more pubs could reopen with less restrictive social distancing, which could avoid closures and staff losing work.
Figures from the British Beer and Pub Association figures show that, with the current two metre rule, only 20 to 30 per cent of premises will be able to open at a sustainable level.
However, if the rule was reduced to one metre, 70 per cent would be able to open.
Meanwhile, the Chartered Institute of Environmental Health (CIEH) stressed the 'vital' importance of the two-metre distance as more businesses prepare to open.
The professional body, which represents those who work in environmental health roles such as in the food, housing and transport industries, urged the Government to maintain the two-metre guidance especially as 'riskier' businesses including pubs prepare to open.
Mr Johnson said his 'own hope' was to reduce the two-metre rule as the spread of coronavirus slows.
On Tuesday Number 10 said the Government believes the two-metre rule should remain in place after asking scientists to look over the evidence.
The Prime Minister's official spokesman said the matter is 'under review' but added: 'The current guidance is the two-metre rule should remain in place.'
England's chief medical officer Chris Whitty says he believes social distancing will be in place 'for as long as this epidemic continues'.
However, scientists have questioned why Britain - with only Spain - is the only European country with the two-metre rule.
The World Health Organisation advises that one metre is sufficient, and France, Sweden and Austria follow the UN's guidance.
Germany, Poland, the Netherlands and Australia all deem 1.5 metres as sufficient.
Professor Noakes said almost every country that was below two metres had introduced other measures, such as mandatory facemasks on public transport.
It is voluntary in the UK to wear a face mask, and this guidance was only updated in mid-April.
Co-author of the WHO study Dr Derek Chu, from McMaster University, said: 'We believe that solutions should be found for making face masks available to the general public. However, people must be clear that wearing a mask is not an alternative to physical distancing, eye protection or basic measures such as hand hygiene, but might add an extra layer of protection.'
Previously scientists have said the two-metre rule lacks any validity.
Professor Robert Dingwall, who sits on the government’s scientific advisory body New and Emerging Respiratory Virus Threats Advisory Group, which feeds into SAGE, said the two metre rule 'has never had much of an evidence base', suggesting it is safe to stand closer to someone.
Former chancellor Norman Lamont said halving the rule to one metre was 'the single most important measure we must take' to avoid 'devastating mass unemployment'.
He said: 'The onus is on the (Government's) advisers to explain why it is that, while Britons must stay two metres apart, the World Health Organisation recommends one metre - as do many other European countries, acting on their scientists' advice.'
Last Thursday, Mr Johnson reiterated his support for the two metre rule, saying: 'I must stress that to control the virus, everyone needs to stay alert, act responsibly, strictly observe social distancing rules, and stay two metres apart from those who you do not live with.'