Video report by ITV News Science Editor Tom Clarke
One in four adults in England have now had their first dose of a coronavirus vaccine, the prime minister has said.
Boris Johnson said "great strides" have been made in the UK's vaccine rollout, but there are two million people "we still hope to reach" before the government can reach its target of vaccinating 15 million people considered most vulnerable to coronavirus by February 15.
Earlier the government revealed at least 13,058,298 have so far received their first dose of a coronavirus vaccine, with 519,553 of those having had a second jab too.
It will be a "long and hard road back to normality", Mr Johnson said, but "if we can keep the pace up and keep the supplies of vaccines up we hope to reach everyone in cohorts one to nine by the end of April".
Mr Johnson said anyone in the top four priority groups who have not been offered a vaccination by the NHS, should get in touch to request one.
On the vaccine rollout so far, Mr Johnson said over 90% of everyone over 75 had received a jab, as have over 90% of eligible residents of care homes for the elderly.
ITV News Science Editor on WHO recommending the Oxford/Astrazeneca vaccine for all adults
The PM issued a particular appeal to social care workers who still have not been vaccinated to contact their employer to "fix it up".
Mr Johnson confirmed a third dose of vaccine, or a "booster jab", is likely to be needed in the autumn to combat the emergence of new Covid variants.
He said coronavirus vaccines could be thought of like flu vaccines, of which the elderly and vulnerable will receive a jab each year.
Mr Johnson also welcomed the World Health Organisation's support for the UK's strategy of delivering the Oxford/AstraZeneca vaccine.
The PM told the Downing Street press conference: "It was good to see the World Health Organisation today confirm its support for the Oxford/AstraZeneca vaccine for use in everyone over the age of 18 and obviously everyone over 65 and also supporting the 12-week interval between the two doses.
"Indeed they say the longer interval provides greater protection."
Ministers will consider what the UK's route out of restrictions should be, with a plan due to be set out on the week commencing February 22.
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It is expected that some primary schools will open around two weeks later, on March 8, if the UK reaches its vaccination target.
Chief scientific adviser Sir Patrick Vallance has said that coronavirus infections and hospital admissions are continuing to fall.
Sir Patrick told a No 10 news briefing that they were translating into a fall in the numbers of deaths which were now below the peak of the first wave of the pandemic.
"All of the numbers are trending in the right direction, coming down quite well because of the effects of lockdown," he said.
But ministers have been warning the public to continue sticking to the rules, even as more and more of the population are vaccinated, because hospital admissions for Covid, and deaths, are still much too high.
A further 1,001 fatalities were recorded on Wednesday, bringing the UK's official coronavirus death toll to 114,851.
Separate figures - published by the UK’s statistics agencies for deaths where Covid-19 has been mentioned on the death certificate - show there have now been 133,000 deaths involving Covid-19 in the UK.
Watch the press conference in full: