The UK hit the milestone of 15 million vaccine injections on Sunday as a senior government minister rejected demands from MPs in his party to lift all coronavirus restrictions by the end of April.
Prime Minister Boris Johnson praised the "extraordinary feat", little more than two months after the first vaccine was injected into the arm of Margaret Keenan, 90, on December 8.
Mr Johnson is scheduled to set out his plans to take the country out of lockdown on February 22, but colleagues rejected demands from within the ruling Conservative Party to rapidly lift social and work restrictions.
More than 60 MPs in the party have called on Mr Johnson to commit to a strict timetable for ending controls in England, including schools reopening by March 8 and pubs and restaurants the following month.
Foreign Minister Dominic Raab said it was too early to say the demands could be met and that the government would be guided by hospital and infection data.
The UK has far outstripped its European neighbours in administering inoculations.
It has a strategy of delivering the first of the two shots required for maximum immunity, to give as many people as possible some protection.
Nadhim Zahawi, the minister in charge of the vaccine programme, said on Sunday that 15 million doses had been delivered, including to all people aged over 70.
Only in Israel and the UAE have more doses been given per capita, non-profit group Our World in Data said.
“We do need to be very careful how we proceed,” Mr Raab told Sky News. “We have made good progress. We don't want to see that unravel because we go too far too quick.
"We are not making what feels to me like a slightly arbitrary commitment without reviewing the impact that measures have had on the transmission and the hospital admissions of the virus.
"I don't think you can set an arbitrary target and not be evidence-led, which is why the review point on February 22 is so important."
He said he was confident that schools would start to reopen on March 8.
The opposition Labour Party has called for the use of better face masks – of the type being recommended in Germany, Austria and France – on public transport and in shops.
“We should be investing in ventilation and air-filtration systems for public buildings,” said Jon Ashworth, the party’s health spokesman.
