A sharp drop in infections has already stalled, they say – with Chris Whitty, the chief medical officer, having suggested they could stay at around 3,000 a day for nine more months, they pointed out.
“If we carry on with 100 to 150 deaths a day, that’s over 30,000 deaths,” warned Christina Pagel, professor of operational research at University College London.
In a new analysis, it said so-called “Super Saturday” on 4 July – when pubs, restaurants and cultural venues can reopen – will arrive before the country is ready for the “risk” it poses.
“We are adding a lot of risk all at once in the context of infections not reducing anymore and test and trace not fully functioning,” Prof Pagel warned.
“They are sending a message that the pandemic is over – and it’s not over.”
Pointing to a “massive surge” in cases in the US and a leap in Germany after curbs were lifted, she added: “I am worried that we will be in a situation here where we don’t spot these increases until it’s too late.”
David King, the former chief scientific adviser, urged venues to impose their own restrictions, saying: “I would ask publicans only to serve people outdoors.”
And Gabriel Scally, professor of public health at the University of Bristol, urged the prime minister to come up with a clear strategy “for the next nine months”, by the end of the summer.
“That’s what the people of this country deserve – we can’t go on with uncertainty and hoping things will be alright,” he argued.
The Department of Health and Social Care said 43,414 people had died in hospitals, care homes and the wider community after testing positive for coronavirus in the UK as of 5pm on Thursday, up by 186 from the day before.
The government figures do not include all deaths involving Covid-19 across the UK, which are thought to have passed 54,000.
The prime minister displayed nervousness about a “serious spike” in infections if people took what he called “liberties” when restrictions are further lifted next weekend.
Mr Johnson is in the firing line for the overcrowded scenes on beaches in Bournemouth and elsewhere, after telling one MP in a seaside town to “show guts” when he expressed fears earlier this week.
But his spokesman said he stood by his wish for sunseekers to go to the beach – provided they obeyed social distancing rules – and backed away from threats the government might close some.
Later, speaking at a London restaurant that is poised to reopen, the prime minister said: “If you look at what’s happening elsewhere in the world where people have been coming out of lockdown, I’m afraid what you’re also seeing is people taking too many liberties with the guidance, mingling too much, not observing social distancing.
“So, in some parts of the world – I won’t name them – you have got spikes, really serious spikes, in the instance of the disease, so it is crucial that people understand that on July 4 we get this right, we do this in a balanced way.”
The UK is emerging from “our long national hibernation”, as Mr Johnson put it, with infections at a much higher level than other EU countries which are unlocking.
Independent Sage warned that:
* A “steady decline in new cases since April has stopped” – with 2,000-4,000 new infections each day.
* The test-and trace system was only catching and obtaining contacts from about one-third of people with symptoms.
* It was also failing to provide any data on how many people contacted are isolating – or how many go on to develop symptoms and get tested.
Prof Whitty made his comments about the infection rate remaining at a similar level when looking uncomfortable at Tuesday’s final daily briefing with the prime minister.
“I would be surprised and delighted if we weren’t in this current situation through the winter and into next spring,” he warned.
“I expect there to be a significant amount of coronavirus circulating at least into that time and I think it is going to be quite optimistic that for science to come fully to the rescue over that kind of timeframe.”
He underlined that stance on Friday, saying: “Covid-19 has gone down due to the efforts of everyone but is still in general circulation. If we do not follow social distancing guidance then cases will rise again.”
The number of UK fatalities passed 50,000 at the start of the month, the third highest in the world behind only the US and Brazil, although international counting methods do vary.
Independent Sage was set up by Sir David King amid criticism that the official Scientific Advisory Group for Emergencies is not transparent and does not reflect the breadth of expertise.
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