People in their late 30s can book a Covid jab from Thursday, say NHS chiefs.
Appointments will open to those aged 38 and 39, in the latest rollout of the programme.
Under new advice from the Joint Committee on Vaccination and Immunisation (JCVI) those in their 30s will be offered Pfizer or Moderna, rather than AstraZeneca.
Around one million people will be sent text messages from Wednesday, so they can access national booking services, which will send them to vaccine sites with these jabs.
Almost three quarters of people in their 40s have now had their first dose.
More than two thirds of adults have now had one dose of vaccine, while one third have had two.
The group will be offered Pfizer or Moderna due to the extremely rare blood clots, including some affecting the brain, linked with the AstraZeneca vaccine.
The same recommendation has been made for pregnant women, who will also be able to access national booking service from Thursday, to ensure they are sent to sites with Pfizer and Moderna.
NHS national medical director Professor Stephen Powis, said: “The success of the NHS Covid-19 vaccination programme is not by accident but down to the careful planning and precision of NHS staff who have now delivered over 45 million first and second doses in the fastest and quickest vaccination drive in NHS history.
“With nearly three quarters of people in their 40s having already received their first jab, the NHS is opening up to people aged 38 and 39 from tomorrow.
“We must not forget that behind the huge numbers of people jabbed, there has been a huge amount of hard work from our staff, aided by incredible volunteers across the country. We are incredibly grateful for their efforts.
Matt Hancock, the Health and Social Care Secretary, said: “Our incredible vaccination programme has already saved thousands of lives and has helped to significantly reduce hospital and infection rates, allowing us to begin safely easing restrictions.
“Vaccines are our way out of the pandemic and I’m delighted we are now inviting people aged 38 to 39 to get their jabs. I urge everybody to get the vaccine as soon as they are eligible to protect yourself and your loved ones.”