Boris Johnson has said he is “optimistic” he will be able to set out plans for a “cautious” easing of coronavirus lockdown restrictions in England later this month.

The Prime Minister said that while the overall number of cases remained high, the infection rate was starting to fall while the rollout of the vaccination programme has made “huge progress”.

“I’m optimistic, I won’t hide if from you. I’m optimistic but we have to be cautious,” he told reporters during a visit to a vaccine manufacturing facility in Teesside.

His comments came as scientists continued to urge caution over the easing of the current controls when Mr Johnson sets out his “roadmap” out of lockdown for England on February 22.

One scientist advising the Government said ministers risked a third wave of the pandemic as big as the current one if they moved too quickly while senior NHS figures said the health service remained under huge pressure.

Ministers however are confident the vaccination programme is on track to meet the target of getting an offer of a jab to everyone in the top four priority groups – including the over-70s – by the deadline of Monday.

Mr Johnson said the efficacy of the vaccines in helping to drive down infection rates would be the key to determining how quickly they could ease restrictions.

“Although the number is beginning to come down and perhaps starting to come down quite fast we need to look at the data very, very hard,” he said.

“Something also that will be very important is the efficacy of the vaccines – are they working in the way that we hope that they are – and making sure they are really helping, along with the lockdown, to drive down the incidence. That is the key thing.”

The Prime Minister said that the Government’s priority remained the opening of schools in England on March 8, to be followed by other sectors as conditions allowed.

“Our children’s education is our number one priority, but then working forward, getting non-essential retail open as well and then, in due course, as and when we can prudently and cautiously, of course we want to be opening hospitality as well,” he said.

“I will be trying to set out as much as I possibly can, in as much detail as I can, always understanding that we have to be wary of the pattern of disease. We don’t want to be forced into any kind of retreat or reverse ferret.”

The Prime Minister, who was visiting the Fujifilm Diosynth Biotechnologies plant in Billingham where the new Novavax vaccine will be manufactured, echoed Health Secretary Matt Hancock who suggested a combination of vaccines and therapeutics could make Covid-19 a “manageable disease” like seasonal flu.

“A new disease like this will take time for humanity to adapt to but we are,” he said.

“I do think that in due time it will become something that we simply live with. Some people will be more vulnerable than others – that’s inevitable.”

Earlier, Professor Steven Riley, a member of the Spi-M modelling group, warned that while the rollout of the vaccination programme had been “incredibly successful” it did not mean controls could simply be dropped.

“No vaccine is perfect. I think scientists are genuinely worried. We don’t want to show that it is an excellent but not perfect vaccine by having another large wave in the UK,” he told the BBC Radio 4 Today programme.

“If for some reason we were to choose to just pretend it (coronavirus) wasn’t here any more, then there is the potential to go back to a wave that is a similar size to the one that we are in now.”

Meanwhile, NHS Confederation chairman Lord Adebowale expressed concern that March 8 was still too soon for schools to return.

He said the NHS workforce was “on its knees” and “cannot afford another peak.”

“I understand the pressure to open schools. We need to do so very safely. I think mid or late March is when we should be reassessing,” he told the Today programme.

However, Mr Johnson remains under pressure from some Tory MPs to get on with lifting the restrictions and reopening the economy as quickly as possible.

Former cabinet minister David Davis said: “There will come a point where there will be a death rate from Covid but it is at a normal level and then we have to cope with that. Obviously we still try to prevent it but we accept it.”