Boris Johnson has been speaking to broadcasters during a visit to a prison, APA reports citing BBC.
He says the UK's booster programme is the "fastest in Europe" and says "I think we've done more boosters than any comparable country".
But he says this does not mean it could not go faster.
He says from Monday the interval between a person getting their second dose and being able to get their third or booster dose will be reduced to three months - in line with the recommendation from the Joint Committee on Immunisation and Vaccination.
"You go down to three months and that will mean a big uptick as well," he says, as he urges people that "now is the time to get it (the jab)".
The prime minister is also asked about reports of a party at Downing Street during lockdown last year but he insists that no rules were broken.
"What I can tell you is that all the guidelines were observed - continue to be observed," he says.