Following the confirmation of the Covid-19 Omicron variant reaching UK shores, it is hoped the vaccination program will be the main line of defence against its spread.

During Saturday's press conference, Prime Minister Boris Johnson said he planned to “boost the booster” campaign and it has since been announced all people aged 18 and over are to be offered a Covid-19 booster vaccine.

The changes, which come as part of efforts to tackle the spread of the new Omicron variant, mean millions more people in the UK have become eligible for a third booster dose.

Early evidence has suggested higher antibody levels may protect better against the variant leading to the Joint Committee on Vaccination and Immunisation (JCVI) advising that all adults aged 18 to 39 should be offered a booster dose. Those aged 40 and over were already eligible for a booster vaccine.

READ MORE: Omicron variant symptoms: What are the symptoms of the new Covid variant

Booster doses should be given no sooner than three months after people have had their second dose of an original vaccine – shaving three months off the original six-month wait, according to the JCVI.

Health Secretary Sajid Javid told the Commons he accepted the JCVI advice in full, adding: “With this new variant on the offensive these measures will protect more people more quickly and make us better protected as a nation.

“It represents a huge step up for our vaccination programme, almost doubling the number of people who will be able to get a booster dose to protect themselves and their loved ones.”

Speaking at a Downing Street briefing, England’s deputy chief medical officer Professor Jonathan Van-Tam said: “I think it’s true to say that scientists around the world, not just in the UK, unfortunately agree that this one is of increased concern.

He added the booster campaign has “never been more vital than at this point in time”.

Professor Wei Shen Lim, chair of the JCVI told the briefing there was an increased likelihood of a “mismatch” between current vaccines and the variant, which may reduce the effectiveness of vaccines.

However, he said a boost of either Moderna or Pfizer could really push up the immune response, and cutting the time between doses could mitigate any drop in vaccine protection.

“If we can raise the level of immune response of the vaccine, that higher level of immune response will reach out and provide an extra level of protection to mismatched variants,” he said.

The expert said there was also a need to deploy booster vaccines “before the wave starts” with any new variant, which is why the new expansion of the vaccine programme is being brought in.

In a speech to the King’s Fund annual conference on Monday, Amanda Pritchard, chief executive of the NHS in England, said NHS staff will “move heaven and earth to vaccinate as many people as possible” to ensure that people can enjoy Christmas with their loved ones."

READ MORE: Omicron variant: All people aged 18 and over in the UK offered Covid booster jab

While the NHS ‘Grab-A-Jab’ website list a walk-in vaccination site on the Isle of Wight and several more further afield in Hampshire, it is important to check which type of vaccinations each site is offering and to whom.

For example, some centres may only offer first or second does while others may only be administering AstraZeneca, or only cover certain age groups.

As this is subject to change it is important to visit the NHS website for the most up-to-date information.

COVID-19 walk-in vaccination site on the Isle of Wight

Riverside Centre
The Quay, Newport, PO30 2QR
This site is for these age groups: 16 and over

COVID-19 walk-in vaccination sites in Hampshire

University Health Service
Building 48, University of Southampton, Southampton, SO17 1BJ
This site is for these age groups: 16 and over

Oakley Road
Oakley Road, Southampton, SO16 4GX
This site is for these age groups: 16 and over

AR Pharmacy
3 Hazel Farm Road, Totton, SO40 8WU
This site is for these age groups: 40 and over

Eastney Health Centre
Highland Road, Southsea, PO4 9HU
This site is for these age groups: 16 and over

St James Hospital
Nelson Drive, off Edenbridge Road, Southsea, PO4 8PF
This site is for these age groups: 16 and over

Southwood Practice
Southwood Village, Links Way, Farnborough, GU14 0NA
This site is for these age groups: 18 and over

READ MORE: UK Covid: Does the vaccine work against Omicron variant?

:: For the most up to date information on what each walk-in vaccination site can offer, visit the NHS Grab-A-Jab website.