Booster jabs to protect against Covid are now available at walk-in sites in England as the NHS hopes to bolster uptake ahead of a “challenging” winter.
About 30 million people who had their second vaccination more than six months ago will be able to get a booster without needing to make an appointment.
The NHS online walk-in finder will let people check their nearest centre.
More than six million people have already had a booster jab or a third dose, NHS England said.
A booster is an extra dose to help people who have been double-jabbed retain their immunity.
Separately, a third dose is a top up for those who may not have had a full immune response from the first two doses. These are being given to people with severely weakened immune systems.
Those entitled to a booster jab include people aged 50 and over, care home staff and residents, and frontline health and social care workers.
Also included are people aged 16 to 49 years old with underlying health conditions which put them at greater risk of severe Covid, and adults sharing a home with vulnerable people.
The top-up will be available at hundreds of sites across England, and NHS England said nearly every person registered with a GP practice lives within 10 miles of a fixed vaccination site.
Dr Nikki Kanani, a working GP and also deputy lead for the NHS Covid-19 vaccination programme, said: “The booster is not just nice to have, it is really important protection ahead of what we know will be a challenging winter.”
Prime Minister Boris Johnson said during his trip to the G20 summit in Rome on Sunday: “I think rather than thinking [about] new restrictions, the best thing everybody can do is get that booster jab as soon as you’re offered it.”
“I think people don’t quite realise that the first two jabs do start to wane,” he said.
“How sad, how tragic it would be if people who had other complications, other compromises in their health, got seriously ill because they were overconfident about their level of immunity and didn’t get their booster when they needed it.”
More than 45 million people in the UK have been double-vaccinated, according to latest government figures., and nearly eight million have received a booster or third dose.
The new drive for booster jabs for certain groups comes as health teams start visiting more than 800 secondary schools in England to offer single doses of the coronavirus vaccine to 12 to 15-year-olds.
Health Secretary Sajid Javid said the vaccines “will help keep children in the classroom”.
The UK’s chief medical officers recommended in September that children aged 12 to 15 be offered one dose of a Covid vaccine.