Boris Johnson has appealed to the five million people who have not taken up the offer of a Covid vaccine to finally get the jab in an effort to avoid tougher restrictions over the winter.

As the Prime Minister launched his plan to “live” with the disease through the coming months, his chief scientific adviser Sir Patrick Vallance said getting vaccination levels up was the key to maintaining lighter controls.

At the same time, chief medical officer for England Professor Chris Whitty launched a stinging attack on people who deliberately peddled “myths” about the supposed dangers of the jab knowing they were untrue.

“In my view they should be ashamed,” he said.

Earlier, Health Secretary Sajid Javid confirmed all over-50s in the UK – as well as those in other vulnerable groups – would be offered a booster shot to maintain protection levels as the country enters the autumn.

Mr Johnson said he hoped the vaccination programme meant the UK could remain “one of the most free societies” in Europe with only limited restrictions to keep the disease in check.

However, he stressed the Government stood ready with a “plan B” for England if the disease took off again over the coming months.

He said it could include mandatory Covid certification – so-called vaccine passports – as well as the return of face masks in public places and encouraging people to work from home.

Sir Patrick said that if additional measures were required it was essential that ministers acted swiftly and did not wait for the numbers to run out of control.

“When you make a move, you have to go earlier than you think you want to, you have to go harder than you think you want to and you have need to make sure you have got the right geographical coverage,” he said.

“So, if this goes in the wrong direction and cases go up, followed by hospitalisations, it’s important that the measures are put in place early enough and they are significant enough.”

If the country had gone into last winter – before the vaccinations were available – with the current level of restrictions, cases would, he said, have gone “through the roof”.

He said it underlined the importance of getting the vaccine to as many people as possible.

“There are five million or so people who are eligible for vaccines now who haven’t been vaccinated,” he said.

“Trying to persuade those people it is the right thing to do to get vaccinated would make a significant difference.

“The immunity is really important to keep this down and allows lighter measures to be put in place to keep it under control.”

Mr Johnson added that the “priority” was to get those people vaccinated insisting that it was in their own interests to get protected.

“It will be good for you. You are overwhelmingly more likely sadly to die or suffer serious disease if you haven’t been vaccinated,” he said.

Mr Johnson said the Government’s plan B had “a number of different shots in the locker” with which it could respond if cases started rising.

“You wouldn’t necessarily play them all at once, far from it, you would want to do things in a graduated way,” he said,

“We’re now in a situation when because so many of the population have some degree of immunity, smaller changes in the way we’re asking people to behave can have a bigger impact.”

While he did not want to see vaccine passports required for entry into nightclubs and other venues, as the Government had previously proposed, he said it was “not sensible” to rule it out at this stage.

“The reason for wanting to have this option is because it’s a choice between proceeding with Covid-19 certification or, sadly, once again asking places to close, and I certainly don’t want to do that.

“That’s why I think it’s a good idea to keep this in reserve.”

Prof Whitty emphasised that the county was entering the autumn with a much higher level of cases, hospital admissions and deaths than was the case last year.

He said that while people were entitled to hold “strange beliefs” about the vaccines, spreading false rumours about their supposed effects was putting lives at risk.

“Many of those people, I regret to say, I think know that they are peddling untruths, but they still do it.

“In my view, they should be ashamed,” he said.

With the booster jab campaign due to start next week, Sir Patrick that while the vaccines’ effectiveness was generally holding up “very well”, there was evidence that it was fading, particularly those who were most vulnerable.

“The waning of immunity is clear.

“It’s greater for infection than it is for the waning against hospitalisations and deaths, so they’re holding up very well,” he said.

“This is some waning.

“And that waning is most evident in the people who are most at risk.”

Under the booster programme, people will be offered either the Pfizer/BioNTech or the Moderna vaccine at least six months after their second dose in order to maximise the impact.