Some 391,246 people received their second dose on Saturday, meaning a total of 20,103,658 people (38.2% of all adults) have now received two injections.
Also on Saturday, 237,331 had their first stroke, bringing the total number of people who received at least one dose to 36,573,354 (69.4% of the adult population).
The government has said it remains on track to deliver a first dose to all adults in the UK by the end of July.
Health Secretary Matt Hancock said: “We have more good news regarding the immunization rollout and are making extraordinary progress, with 20 million people now enjoying the most comprehensive protection possible against this virus – a huge thank you to the team for taking this step.
“The latest real-world data has once again demonstrated how effective the vaccine is in providing life-saving protection, with two doses of the Pfizer vaccine providing 97% protection against mortality.
“Receiving a second dose is vital to ensuring you have the ultimate protection against this deadly virus – I encourage everyone to reserve their jabs as soon as offered. “
In Wales, it has been reported that more than two million people have now received a vaccine.
Almost three million doses in total were administered in the country in six months. This means that 80% of all adults in Wales have received their first vaccine and one in three adults have received their second dose.
Meanwhile, the UK has reported four more coronavirus-related deaths and 1,926 new cases in the last 24-hour period.
That compares to seven deaths and 2,027 cases announced on Saturday, while last Sunday two deaths and 1,770 cases were reported.
Since the start of the pandemic, a total of 127,679 people have died in the UK within 28 days of testing positive for COVID-19, and there have been 4,450,777 laboratory-confirmed cases.
The latest data has been released as Mr Hancock said there is a “high degree of confidence” that vaccines protect against the Indian variant – but it can “spread like wildfire” among those who haven’t had a bite.
He said the Indian variant “was becoming the dominant strain in parts of the country” like Bolton and Blackburn.
Mr Hancock warned it could ‘spread even faster’ than the Kent variant, which led to the second deadly wave of infections in the UK this winter, with a total of just over 1,300 cases found in the country so far.
He also claimed that it was “appropriate” to continue the Major easing of restrictions in England on Monday despite scientists’ concerns that it may be 50% more transmissible than the Kent strain.
And he urged those who are eligible for vaccination – but have not yet made an appointment – to get vaccinated, adding he did not rule out imposing local lock restrictions in the places most affected by the Indian variant.
Meanwhile, Blackburn’s director of public health with the Darwen Council, Dominic Harrison, tweeted he was “delighted” that “we now have the” green light “to ramp up vaccinations quickly.
He wrote: “An additional supply of over 1,000 per day (Pfizer) for the next 2 weeks for the two high-spread variant areas and all residents over 18 (subject to eligibility). ”