The government may already have exceeded the “absolute limits” of easing lockdown restrictions, an expert has claimed.
Wellcome Trust director Jeremy Farrar said on Sunday there were “worrying signs” that coronavirus infection rates could be on the rise.
Farrar, a member of the Sage advisory committee, also said that ramping up testing is essential to keeping the virus under control.
“The gradual uptick in cases has shown us we’ve now reached, if not already exceeded, the absolute limits of easing restrictions,” he wrote in The Observer.
“The R value, which tells you how many people will get the virus if in contact with an infected person, is close to 1. There are worrying signs that we’re in danger of heading in the wrong direction.
“Most urgently, we need to ramp up testing. We are not where we need to be. We must improve contact tracing, so we’re identifying more cases and providing better, faster data locally.
“We need to make it much easier for everyone to get tested, including those who have been in contact with cases or think they might be infected, whether they have symptoms or not.”
Farrar’s sentiment was echoed by Professor Chris Whitty, the chief medical officer for England, who warned the nation has "probably reached near the limit or the limits" of what can be done to reopen society safely.
And Professor Neil Ferguson, whose modelling led to the decision to impose the lockdown, suggested ministers would need to "row back on the relaxation of restrictions" to allow a full-time return to schools while keeping the virus under control.
It comes as as experts warned that pubs, with their typically poor ventilation, noise necessitating loud voices, and social environments, could carry a greater transmission risk than planes.
"It is a perfect storm aided and abetted by alcohol the enabler," one of the scientists, Dr Bharat Pankhania, a senior clinical lecturer at the University of Exeter, told the PA news agency.
Mixing in pubs and homes was blamed for a rise in cases in Preston, the latest local area to have restrictions reimposed.
Preston recorded 49 new cases of coronavirus in the week to 31 July, more than double the week before when there were 22 – this meant almost 35 cases per 100,000 population.
Leicester became the first UK city to go back into full lockdown at the start of July, just as restrictions were eased across the rest of England.
In recent weeks, areas in Greater Manchester, East Lancashire and West Yorkshire have all entered local lockdowns following localised surges in coronavirus cases.
Figures published last weekend by Public Health England show Swindon, Melton, Eden, Sandwell, Northampton and Peterborough have seen a rise in coronavirus infections but have not faced further lockdown measures.
Last week, Boris Johnson halted the lifting of further lockdown measures, saying the government now has to "squeeze that brake pedal".
“The prevalence of the virus in the community, in England, is likely to be rising for the first time since May,” said Johnson.
“That means until August 15 at the earliest casinos, bowling alleys, skating rinks and the remaining close-contact services must remain closed.
“Indoor performances will not resume, pilots of larger gatherings in sports venues and conference centres will not take place, and wedding receptions of up to 30 people will not be permitted.”
A further 758 cases were confirmed across the UK on Saturday and there have been 46,566 deaths in the UK from coronavirus since the start of the pandemic.