Scientists advising ministers have warned against lockdown being lifted too quickly as a senior Tory MP said the Government should be “looking to open up” society.

Professor Graham Medley, chairman of the Scientific Pandemic Influenza Group on Modelling (Spi-M), said ministers should “make decisions dependent on the circumstances, rather than being driven by a calendar of wanting to do things”.

He was backed by Dr Mike Tildesley, also from Spi-M, who said there needed to be a gradual easing out of lockdown to prevent a resurgence of cases and the need to implement tighter controls.

But Sir Graham Brady, chairman of the backbench 1922 Committee, said the country was in a “far more optimistic place”, citing falling infection rates and the vaccine rollout.

“We don’t want the Government to be behind the curve if things continue moving as positively and as rapidly as they are,” he told BBC Radio 4’s Today programme.

The lockdown-sceptic MP said the argument for England’s third national lockdown was to stop the risk of the NHS becoming overwhelmed, but said the health service had “coped spectacularly well”.

“Now that that threat is receding, we ought to be – and indeed we are, and the Government says we are – looking to open up,” he added.

It comes after former health secretary Jeremy Hunt told the Guardian that ministers should take a cautious approach to lifting the lockdown so that new coronavirus cases can be driven down to 1,000 a day.

Speaking to the Today programme in a personal capacity, Prof Medley said watching case numbers was still important even though vaccines would protect the elderly and most vulnerable.

“Vaccination offers a way out and does reduce the impact of infection, but it doesn’t remove it completely,” he said.

“And so case numbers are still important because they represent the risk of having to go back into some kind of national measures.”

Asked whether case numbers needed to be as low as 1,000 a day, he said: “Clearly the lower the numbers of cases are, the more time you have to react if things start to go badly wrong.

“If the case numbers are very high, if they’re as high as they are at the moment, for example, then you will have very little time in which to react to avoid the kind of national lockdown that we’re in at the moment, which nobody wants.”

Dr Tildesley told Times Radio it was important “to avoid a yo-yo situation where we unwrap things too rapidly, we get a resurgence and we have to lock down again”.

He added: “The real concern here and where we really need to be careful is that it all comes down to R number.

“As soon as we start to relax, things go up. The key thing for me is we need to get our children back to school first – that’s clearly the most important thing.

“But I would really encourage it needs to be gradual stepping out of lockdown so that we don’t get a resurgence as we move into the spring.”

I really appreciate the need for people getting back some level of normalcy. My concern is a resurgence by doing that, which will lead to a much greater problem as we get into the spring

Pressed on whether outdoor socialising next month seemed reasonable, he said “a little bit more mixing outdoors” might be reasonable but would need “very clear messaging from the Government”.

He added: “I really appreciate the need for people getting back some level of normalcy. My concern is a resurgence by doing that, which will lead to a much greater problem as we get into the spring.”

Dr Tildesley said the Government would need to look at national case rates per day for unlocking, as well as local rates, plus hospital occupancy and the R rate.

Speaking to the BBC news channel, Dr Ian Higginson, vice president of the Royal College of Emergency Medicine, said his organisation “could not be more firmly in camp caution… this could all go Pete Tong really easily”.

In his interview with the Guardian, Mr Hunt, who is chairman of the health select committee, said the Government should aim to suppress Covid-19 cases so that intensive contact tracing can work.

Mr Hunt said: “The Koreans and the Taiwanese have kept their economy open. All their restaurants are open, because they’ve kept case transmission low, and we just need to do what it takes to get to that point.

“And for me, where I’m at on that is that you just need to get it down to 1,000 new infections a day or less.”