Another lockdown could still happen and ministers should 'leave the door open' for Covid curbs, a disease expert has said.
Professor of infectious disease epidemiology Mark Woolhouse urged the government to keep the possibility of future restrictions on the table.
He said as the virus evolves ministers would need to respond in whatever way was needed to fight the disease.
The remarks come nearly three weeks after so-called Freedom Day saw the vast majority of coronavirus restrictions lifted in England on July 19.
New Covid cases have been steadily above 20,000 per day for the last two weeks, but are down from the soaring highs that saw more than 40,000 new cases every day in mid-July.
The most recent data shows that there were 27,429 positive cases recorded on Sunday.
In an interview with Times Radio, the University of Edinburgh scientist said: "For people like myself, trying to advise the government on how to proceed and how fast to unlock, this determination to never go backwards is actually quite unhelpful.
"It inevitably makes the advice more cautious. Because if we can't go backwards we're very, very cautious about unlocking.
"What I think we need, because we're dealing with a novel virus with still uncertain potential, and we don't know how much this thing will evolve in the future, is to leave the door open to responding in whatever way is necessary in the future.
"I very, very much hope we won't have to go backwards, at least not too far, but I think we have to have that possibility, and keep it open just in case there is a public health emergency that none of us have foreseen at this stage."
Meanwhile, separate reports have revealed that the government had made "contingency plans" for further lockdowns if the NHS was to become overrun.
A source told the i that ministers and experts remain confident that the vaccine roll-out has broken the back of the pandemic.
But they said that Boris Johnson has authorised planning for a "firebreak" lockdown, for if the situation worsens.
It is thought that a staffing crisis within the NHS and the rise of other diseases - previously beaten back by Covid restrictions - could hamper the health service, along with the potential rise of a vaccine-beating strain.
But a government advisor told the outlet: "Should more lockdowns be necessary, the plan is for them to be short, and preferably during the school holidays in late October and over Christmas.
"Firebreaks rather than lasting for months at a time."
No.10 confirmed contingency plans were in place and did not rule out the prospect of further lockdowns.
