Around five million people in England will be invited to get their spring COVID-19 booster jab from next week.
Care home residents will be the first to receive the booster jab from Monday.
All other eligible people – including the over-75s and young children who are immunosuppressed – will be able to book their jab from Wednesday.
The first appointments will be made available from 17 April.
The initial invitations will be sent through the NHS app, with text messages and letters sent to those without the app or not regularly using it.
NHS director of vaccinations and screening, Steve Russell, said it was “really important” that those at “greatest risk” come forward to boost their protection in the coming weeks.
“As a society, we are learning to live with COVID but, for many, it is still a virus that can cause serious illness and hospitalisation,” he said.
“There are still around 8,000 people in hospital with COVID, according to the latest data, and the NHS has now treated more than one million COVID inpatients since the pandemic began.
“So if you are over 75 or you have a weakened immune system, please come forward as soon as possible to book a COVID vaccine this spring so you can enjoy summer with peace of mind.”
Health Secretary Steve Barclay said: “Our successful vaccination programme has helped us all to live with COVID, saved thousands of lives and protected the most vulnerable from serious disease.
“We’re committed to giving vulnerable people the protection they need from the virus, so I want to encourage those who are 75 or over or who have a weakened immune system to book their booster jab from Wednesday.
“It’s quick and easy and will give the protection you need for the months ahead.”
The Novavax jab will be available for use only when alternatives are not considered clinically suitable.
The vaccine people receive will depend on local supply, though all children under 12 will be offered a children’s formula of the Pfizer/BioNTech vaccine.