Categorised a variant of concern by the World Health Organisation (WHO), the variant, first detected in South Africa, can spread between people who are fully vaccinated.
While scientists are still gathering data on its effects, it is feared the new strain could reduce the protection offered by existing vaccines.
As such, the Joint Committee on Vaccination and Immunisation (JCVI) has now extended the booster vaccination programme to allow all adults in the UK to get a top up dose to try and minimise a rise in infections.
New restrictions have also come into force in England to control the spread, including mandatory face masks in all indoor venues and stricter self-isolation rules.
But who is eligible for a booster vaccine, and how do you book one? This is what you need to know.
When can I get my booster jab?
Everyone aged 18 or over will be offered a Covid-19 booster dose, under new JCVI guidance.
The jabs will be rolled out in order of descending age groups, with priority to be given to older adults and those in an at-risk group.
Those aged 40 and over are currently already eligible to get a booster vaccine. A top-up dose will also be offered to people aged 16 years old and over with a severely weakened immune system.
Guidance states that boosters should be given no sooner than three months after people have received their second jab, halving the previous six month wait between doses.
Those who are severely immunosuppressed should be offered a booster jab no sooner than three months after completing their primary course of three doses.
How do I book my booster jab?
Booster doses will be rolled out in order of descending age groups and should be given no sooner than three months after the second jab.
In England, people should receive a letter or a text inviting them to book their booster vaccine dose when they are eligible. Once you have been invited to book, you can do so online via the NHS national booking system.
If you have had a positive Covid-19 test, you will need to wait four weeks before booking your booster from the date you had the test.
People can also book by calling 119 or get vaccinated at hundreds of walk-in sites across England without an appointment. Those eligible can use the NHS online walk-in finder to find their closest site.
If you are in Scotland, the NHS inform website features a handy tool which explains how you will be invited for your booster vaccination.
In Wales, you will be contacted by your health board when it is your turn to book your jab. You should not contact your GP to ask about appointments.
In Northern Ireland, the booster programme is underway with residents and staff in care homes being offered a dose, while GPs will be inviting their older patients in first to receive their booster. You should wait until you are contacted to book an appointment.
Can I go to a walk-in centre?
Covid-19 booster jabs are available at walk-in vaccinations centres across England without the need for appointment.
From 1 November, anyone who is eligible for a booster can turn up at one of hundreds of jab sites for their top-up.
NHS England has advised people to use its online walk-in finder to check where their nearest vaccination site is.
The health service said almost every person who is registered with a GP practice lives within 10 miles of a fixed vaccination site.
The walk-in finder website will reveal whether a vaccination centre is offering booster doses, vaccines for 12 to 15 year-olds, or anyone aged 16 and over.
To find your nearest walk-in centre offering booster doses, enter your details on the NHS website.
Which vaccine will I get?
Those eligible for the booster will be offered either a full dose of the Pfizer vaccine, or a half dose of the Moderna vaccine.
These vaccines will be used regardless of which jab individuals had for their first two doses as these have both been shown to provide a strong booster response.
In cases when neither of these vaccines can be offered, due to an allergy for example, the JCVI advises that the AstraZeneca vaccine can be used for those who received this jab for their first and second dose.
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