After the government announced a restriction on social gatherings from next week, researchers have warned that the R rate of coronavirus has risen to 1.2.
The figure – which represents the number of infections caused by one person – was described as “worrying” by the team behind the COVID Symptom Study app.
They said that while lockdown brought down coronavirus cases to levels of around 1,000 to 2,000 per day, numbers have risen to 2,500 daily new cases.
It comes as social gatherings of more than six people will be illegal in England from Monday as the government seeks to curb the rise in coronavirus cases.
Video: What is meant by its 'basic reproduction number'?
Boris Johnson is set to formally announce the change in the law after the number of daily positive COVID-19 cases in the UK rose to almost 3,000.
Some 2,420 lab-confirmed cases of coronavirus were recorded in Britain as of 9am on Tuesday, following the 2,988 reported in the UK on Sunday, which was the largest daily figure since May.
While the official government R rate figure currently stands at between 0.9-1.1, Professor Tim Spector, from the ZOE health app, said its their data – from users who log in and say if they are feeling unwell – led researchers to conclude the R value is currently 1.2 for England, Scotland and Wales and 1.3 for Northern Ireland.
The legal limit on social gatherings will be reduced from 30 people to six from Monday and will apply to gatherings indoors and outdoors – including private homes, as well as parks, pubs and restaurants.
Gatherings of more than six people will be allowed where the household or support bubble is larger than six, or where the gathering is for work or education purposes.
Exemptions will also apply for weddings, funerals and COVID-secure organised team sports, with a full list to be published by the government before Monday.
Downing Street said chief medical officer Professor Chris Whitty, chief scientific adviser Sir Patrick Vallance and the government had jointly agreed that urgent action was needed after the rise in coronavirus cases.
The government hopes the change to the law will make it easier for the police to identify and disperse illegal gatherings. Failure to comply could result in a £100 fine, which will double on each repeat offence up to £3,200.
How the rules vary
Different rules apply to social gatherings elsewhere in the UK.
In Scotland, up to eight people are allowed to meet indoors, while groups of 15 from up to five households are permitted outdoors, but people should maintain a social distance.
People should not meet people from more than four other households in total, whether indoors and/or outdoors.
In Wales, up to 30 people can meet outdoors and in Northern Ireland the number is 15.
‘No second wave’
Health secretary Matt Hancock has warned of a potential second wave of coronavirus as cases rise, but an expert on medicine said last week the increase was down to more tests being carried out.
Professor Carl Heneghan of the University of Oxford believes that while a “comprehensive system of national test and trace” has led to an uptick of confirmed COVID-19 cases across the UK, that does not mean the disease is on the rise.
He said “new mild cases” are not infectious, and are simply being picked up by sensitive tests, providing positive results.
Heneghan highlighted how deaths in the UK had remained low and stable, adding that the sensitivity of polymerase chain reaction (PCR) for testing meant the smallest fragments of the virus in a sample are amplified millions of times – providing a positive result even when someone is not infected by the whole virus.
He told The Spectator that these fragments do not make the whole virus and therefore cannot infect other people.