Watch: All over-40s in England can now book COVID vaccine appointments
It is the third time this week that the booking system for Covid jabs has been extended. Appointments were offered to those over 44 on Monday, and to over-42s on Tuesday.
Nearly three quarters of a million appointments were booked at the start of the week as the programme was broadened further, NHS officials said.
And now all over-40s can arrange one via the national booking website.
It comes as figures showed that more than 34 million people across the UK have now received one dose of a vaccine. More than 14 million people are already fully vaccinated.
NHS England chief executive Sir Simon Stevens said: "With nine tenths of people aged 45 and over having been jabbed, nearly three quarters of a million new appointments were made in just two days as our booking service opened to people aged 42 to 44.
"With second doses also proceeding apace, we're now ready to invite all those aged 40 and over to join the most successful vaccination drive in health service history."
The target of offering a first dose to the nine most vulnerable groups by mid April was reached three days early, allowing the programme to be expanded.
Within a week of being invited to book, two-thirds of 45 to 49-year-olds had received their first dose.
Among those in their 40s to get the jab in recent days was Health Secretary Matt Hancock. The 42-year-old urged those eligible to join him in getting jabbed.
Mr Hancock said: "The UK's vaccination programme has been a phenomenal success so far, with more than 47 million doses administered and one of the highest uptake rates in the world.
"Building on this excellent progress we are now opening up vaccinations to 40 and 41 year olds.
"I urge everybody in these age groups to book a jab as soon as possible to protect yourself and your loved ones from this dreadful disease."
Mr Hancock had his first dose administered by none other than deputy chief medical officer Professor Jonathan Van-Tam at London's Science Museum.
Those aged 30 and over are being offered the jab across Wales.
In Scotland, preparations continue to extend the vaccine rollout to people in their 40s.
And in Northern Ireland people aged 35 and over, as well as the clinically vulnerable, have also been invited to book their vaccine appointment.
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