The prime minister is to receive his first dose of the Oxford-AstraZeneca Covid-19 vaccine after reassuring the public it was “safe”.
Boris Johnson, 56, has urged people to get inoculated and said England’s roadmap out of lockdown was “on track”.
He said there was “no change” to the plan despite a drop in vaccine supply.
Several European countries are to resume using the AstraZeneca jab after the European Medicines Agency (EMA) confirmed it was “safe and effective”.
The regulator reviewed the vaccine amid fears about blood clots, but said it was “not associated” with a higher risk and the benefits outweighed any risks.
Mr Johnson told a Downing Street conference on Thursday that the AstraZeneca jab was safe but “the thing that isn’t safe is catching Covid, which is why it is so important that we all get our jabs as soon as our turn comes”.
The prime minister was himself hospitalised with Covid-19 in April 2020 during the first wave of the pandemic.
“The way to ensure this [lockdown easing] happens is to get that jab when your turn comes, so let’s get the jab done,” he said.
Prof Chris Whitty, chief medical officer for England, said there were “anecdotal reports” of small numbers of people not turning up for vaccine appointments following the controversy over the AstraZeneca jab in Europe.
But he said he expected many of those would decide to get the jab after “a pause for thought”, adding that Covid was still a “very dangerous disease”.
“People dying, people getting significant blood clotting problems, that’s one of the risks of Covid, people having long-term physical and mental effects from Covid,” he said.
Mr Johnson said England’s progress towards leaving restrictions on daily life was “unchecked” by vaccine supply issues, where fewer doses have arrived from India than initially expected.
The European medical regulator had reviewed the AstraZeneca jab after 13 European Union states suspended its use over fears about blood clots in a very small number of patients.
Germany, Italy and France are to resume use of the jab on Friday while Spain, Portugal and the Netherlands will do so next week.
Like his UK counterpart, French Prime Minister Jean Castex will receive the AstraZeneca vaccine in an effort to sway a doubtful French public.
In the UK, the Medicines and Healthcare products Regulatory Agency (MHRA) also concluded that any link between the jab and clots was unproven.
The MHRA and the EMA say people can have confidence in the vaccine’s benefits and should get immunised but anyone with a headache lasting more than four days after vaccination should seek medical advice, as a precaution.
That is because the regulators have received a very small number of reports of an extremely rare form of blood clot occurring in the brain.
It is this type of clot that triggered some European countries to pause rollout of the Oxford-AstraZeneca vaccine.
In the UK, five cases of cerebral sinus vein thrombosis (CSVT), among 11 million people who have received the vaccine, occurred in men aged between 19 and 59. One of these was fatal.
The EMA has received an additional 13 reports of CSVT.
The World Health Organization (WHO) has called on countries to continue using the vaccine, and is due to release the results of its own review into the vaccine’s safety later on Friday.