Next week is the last chance adults 49 and under who have not yet received a full set of coronavirus vaccines can take up the offer.
The NHS has said Sunday 12 February is the last day people in this age group can visit a vaccination site for their primary doses, while hundreds of thousands of appointments will be available for booster shots.
After this date, the injections will only be offered to people who are considered to be at risk of serious illness, as recommended by the Joint Committee on Vaccination and Immunization (JCVI).
There are 2,800 locations open nationwide next week, with 391,000 appointments available before the program winds down.
So far 15,000 people have booked a Covid vaccine for next week, the NHS said, after 17.3 million people had a booster shot over the winter.
A total of 144.5 million doses of coronavirus vaccine have been delivered across Britain since the start of the pandemic.
Health and Social Care Minister Steve Barclay and the NHS director of vaccinations and screening, Steve Russell, urged people to seize the last chance to get the shot.
Mr Russell said: “There is only a week left of the fall booster campaign, so if you are eligible for a booster but have yet to take your last dose, do so before the end of next week.
“Whether you have had previous doses or a bout of Covid, we know that a booster is the best way to protect yourself and your loved ones from severe Covid illness, so please take full advantage of the offer while it is available and grant yourself both protection and peace of mind for the coming year.”
Mr Barclay added: “Our hard-working NHS staff and volunteers have done a fantastic job of getting punches in the arms, and they are on hand to boost your immunity and keep you and your loved ones safe.”
The number of coronavirus infections in the UK has fallen for a fourth week in a row and is at a level last seen at the beginning of last autumn.
The number of infections is not falling in all age groups, with increases in England among primary and secondary school children and among those aged 35 to 49.
The recent drop in the number of coronavirus patients in hospital has also stalled, as health experts said there were “troubling” signs that numbers could start to rise.
A total of 941,800 people in private households in the UK were likely to have had Covid-19 in the week ending January 24, 15% down from 1.1 million the week before, according to the Office for National Statistics.
This is the lowest UK total since the week ending September 14, 2022.