People aged 34 and 35 in England will be offered a coronavirus jab from Thursday, the NHS has said.
People in their early thirties could get the chance to be vaccinated "over the next few days and week", NHS England said.
The timetable to vaccinate people has speeded up in some parts of the country because of the increasing risk of the Indian variant, while high-risk people will now have to wait eight weeks between doses – rather than the 12-week period set earlier this year.
Professor Stephen Powis, national medical director for NHS England, said: "The success of the NHS COVID-19 vaccination programme, the biggest in history, is not by accident but down to careful planning and precision by NHS staff who have now delivered 48.5 million doses across England in less than six months.
"Getting the vaccine is the single most important step we can take to protect ourselves, our families and our communities against COVID-19, so when you’re called forward, book your appointment and join the tens of millions who have already been jabbed."
Health Secretary Matt Hancock said that this latest development is "incredible news", as England "remains on track to hit our target of offering a vaccine to all adults by the end of July".
"I’m delighted that 70% of adults across the country have already been vaccinated with their first dose, and 40% with their second," he said.
"We have one of the highest uptake rates in the world but we’ll continue to do everything we can to make sure no one is left behind."
Under-40s have previously been advised to receive an alternative vaccine to the Oxford-AstraZeneca jab due to a small number of blood clots.
This means most under-40s will be offered the Pfizer or Moderna vaccine.
On Wednesday, Mr Hancock said that 2,967 cases of the Indian variant have now been recorded, up from 28% on Monday.
Surge testing and increased vaccinations will be deployed in Bedford, Burnley, Hounslow, Kirklees, Leicester and North Tyneside.
Mr Hancock also announced on Tuesday that thousands of volunteers will get a booster jab as part of the world’s first clinical trial into the effectiveness of a third dose.
The Cov-Boost study will involve seven vaccines and will be the first to provide data on whether a booster jab may or may not be necessary.
Figures released on Wednesday showed 57.8 million vaccines have been administered in England, including 36.9 million people with their first dose – or 70.2% of the adult population.
Meanwhile, 20.8 million people (39.6%) of the adult population had received both doses.
The news comes it was announced the vaccination programme in Northern Ireland was extending to include people aged 25 and over.
NHS leaders in Scotland are encouraging people aged 30 and over to come forward for their jab.
In Wales, some 43% of 18 to 29-year-olds have had their first jab and 62% of those aged 20 to 39 have had their first dose.