Around five million elderly or vulnerable people in England can now book spring coronavirus booster jabs to protect them from the virus.
The UK government's spring booster programme, administered via the NHS, will run from April until June and will look to protect over-75s, people living in care homes, and those considered most at risk of serious effects when contracting COVID-19.
Official estimates of COVID-19 cases show they were at their highest level so far this year at the end of March, according to the most recent data from the Office for National Statistics (ONS).
And according to the independent ZOE Health Study there were 78,361 new symptomatic cases of COVID in the UK on Saturday.
ZOE data revealed that figures have dropped since the end of March peak, but are still consistently higher than in January or February.
Here is what you need to know about the spring COVID booster:
How to book your COVID spring booster jab
All eligible people can book their jab online from 17 April. They will be sent initial invitations through the NHS app, where they can also book their appointment.
Text messages and letters will be sent to those without the app or who are not regularly using it.
Who is eligible for the booster?
Around five million people are eligible for the spring booster, which is targeted at the most vulnerable groups, those at risk of serious illness from COVID-19.
The booster is being offered to people in care homes, those aged 75 or older and those aged five and over with a weakened immune system.
When will they receive their COVID booster?
Some care home residents in England have already received their booster, and all other eligible people can book their jab online, with the first appointments available from Monday.
Which COVID vaccines are being offered?
Last month, the Joint Committee on Vaccination and Immunisation (JCVI) said the spring booster campaign can include vaccination with the Pfizer, Moderna and Sanofi/GSK jabs. The government website page outlining the spring booster programme says that these vaccines have been updated since the original vaccines and now target different COVID-19 variants.
The Novavax jab will be available for use only when alternatives are not considered clinically suitable.
Children under 12 will be offered a children’s formulation of the Pfizer/BioNTech vaccine.
The government said the Sanofi vaccine will only be offered to older people.
Local supply availability will dictate which vaccine people receive.
What have health officials said?
NHS director of vaccinations and screening Steve Russell said: "The COVID vaccine still has a crucial role to play in protecting those at greatest risk of severe illness from the virus, including those with a weakened immune system as well as all aged 75 and above.
“It is great to see that around 320,000 people have booked in to get a jab with around hundreds of thousands of further slots available across the country this week alone.
“The NHS COVID-19 vaccination programme has delivered almost 145 million vaccine doses since December 2020 and staff will not stop in their efforts to give people extra protection.
“I would urge anyone eligible for this extra protection to get their spring COVID vaccination at the earliest opportunity and give yourself peace of mind this summer.”
What has the government said?
Health and social care secretary Steve Barclay said: “As we enter spring, it’s important to remember immunity from COVID vaccines wanes over time. From today, a further one million people will be invited to top up their protection against the virus.
“For the first time, invites to book a COVID jab are being sent via the NHS app – a fantastic example of how we’re using technology to make it easier for people to access health services. With over 3,000 vaccination sites across England, it couldn’t be easier to get your jab when invited so please do not hesitate.
“The offer of a first and second dose of vaccine to healthy adults will also be ending on 30 June and I strongly encourage anyone who has not yet come forward to join the nearly 43 million who have already received both doses.”
Watch: People get their autumn COVID booster jab