More than half of all adults in the UK, and everyone aged over 50, should receive a coronavirus vaccine by May, the government has announced.

Following positive news that the vaccines are safe and effective against the Kent variation of coronavirus, Downing Street said that the vaccine programme planned to reach all those aged 50 and over, as well as adults aged 16-65 in an at-risk group, by May.

Previously they had only said it aimed to do so “by the spring”.

West Suffolk MP and health secretary Matt Hancock warned that “lots of things have got to go right” to hit the goal, including supply, but he said he was “sure” it was achievable. More than 10.9 million first doses have already been given.

According to the government’s vaccines delivery plan, some 32 million people across the UK are estimated to fall into the first nine groups. There are 52.7 million people aged 18 and over in the UK.

Prime Minister Boris Johnson has faced sustained pressure from some Tory backbenchers to relax the measures as soon as possible, but scientists advising the government have warned against opening up too quickly.

In a sign that the current measures are working, the reproduction number, or R value, of coronavirus transmission across the UK fell to between 0.7 and 1, according to the latest Government figures – down from between 0.7 and 1.1 last week.

And estimates from the Office for National Statistics (ONS) suggested about one in 65 people in private households in England had Covid-19 between January 24 and 30 – compared with one in 55 the previous week.

However, a further 1,014 people died within 28 days of testing positive for Covid-19 as of Friday and there were another 19,114 lab-confirmed cases of coronavirus in the UK.

Mr Johnson is due to publish a roadmap for lifting the restrictions later this month.

Any decision to relax the measures will be boosted by new research from Oxford University suggesting its vaccine with AstraZeneca is effective at fighting the new UK coronavirus strain.

Researchers said it has a similar efficacy against the variant, compared with the original strain of Covid-19 against which it was tested, following concern over whether or not the vaccines would continue to be effective.