There would be “a net disadvantage” in transferring Covid vaccines from older people to younger members of the public who are at lower risk from the virus, England’s Chief Medical Officer has said.

Professor Chris Whitty pointed out there is not an endless supply of vaccines and the aim is to firstly protect the most vulnerable from coronavirus, which “is very heavily predicated by age”.

He told a Downing Street press conference: “If we took vaccine away from say groups in their late 30s and transferred them to groups of people who are 18 or 20 who are at much lower risk of severe disease, the view of the JCVI (Joint Committee on Vaccination and Immunisation), has clearly been that this would lead to a net disadvantage overall.

“The sensible thing to do is to prioritise the vaccines to those who are most at risk in all the places across the UK because this virus is a risk everywhere, but there are very strong aims to try and accelerate and make easier vaccination in the areas which are most affected by this virus.”

He also noted that “the fundamental issue is that we have a finite supply at any given time of the vaccine, so if you vaccinate one person by definition you are not vaccinating another.”

His comments came as a Merseyside vaccine centre faced a queue that stretched around the block after it was announced all over-20s would be given a jab.

The centre is at Hirshman’s Chemist in Sefton, near Formby, where there has been a rise in coronavirus cases with the Indian variant.

More than 150 people turned up after a Facebook post announced that all over-20s would be eligible for a jab at the centre after 3pm on Friday.

Earlier, the leader of Bolton Council said they had been in discussions with the Government about the introduction of “surge” vaccinations in the area where there has been a high number of cases of the Indian variant.

David Greenhalgh told BBC Radio 4’s The World At One: “This is an issue of capacity but we have had very, very constructive talks and certainly all the soundings are that they are looking to progress that as soon as possible.

“The vast majority of our cases are in their teens, 20s and 30s at the moment.

“If we can get vaccinations to (those aged) 16-plus, which are licensed by Pfizer, then it will make a total transformation of transmission as it moves forward.”

Prof Whitty told Friday’s press conference that officials have “very high confidence” the vaccines provide very substantial protection against people dying, having severe illness and being admitted to hospital.

He explained there there is “less” protection against people having more mild disease and “some protection but less still against transmission”.

He added: “The expectation is that with new variants if you lose some efficacy you lose it in the opposite direction.

“So in a sense you first lose the very low protection of people having asymptomatic or very mild disease, then you lose the protection against the more severe disease and finally against the most severe disease and people having mortality.”

Professor Adam Finn, of the Joint Committee on Vaccination and Immunisation, agreed that there is not a net advantage to moving the vaccine to younger people who are in a particular location to try to give them extra protection.

He told BBC News: “There is a danger that if you start trying to move vaccines around between places or between people, essentially what you end up doing is robbing from Peter to pay Paul and and you don’t really get any net advantage.

“It is important to recognise that actually getting vaccine into people’s arms and then them getting significant protection does take time, in particular after the first dose you don’t really get any protection in the first two or three weeks after receiving that vaccine.

“You can imagine that you could end up chasing the virus by doing that and just leaving other people who might be in fact in more urgent need of immunisation more vulnerable. You just end up with the problem happening somewhere else.

“Our view is that you really need to continue to move the whole programme forward in step.”