Booster vaccine jabs and third primary vaccines are now available for all eligible people.

Four million booster vaccines have already been administered in the UK and half a million appointments were booked on Wednesday and Thursday last week alone.

The prime minister has insisted vaccines will be the best defence against the disease this winter and has renewed calls for people to get their Covid jabs and booster vaccines.

This is despite warnings from health leaders that tighter restrictions are needed in order to prevent further lockdowns.

Boris Johnson, who has said there are no plans for another lockdown, said: "Vaccines are our way through this winter.

"This is a call to everyone, whether you're eligible for a booster, haven't got round to your second dose yet, or your child is eligible for a dose - vaccines are safe, they save lives, and they are our way out of this pandemic."

Why get a booster jab?

Recent studies have shown the protection offered by vaccines wanes over time.

Protection against death falls from 95pc to 80pc for AstraZeneca after six months and from 99pc to 90pc for Pfizer.

According to Number 10, the booster programme is designed to top up this waning immunity for those most at risk over the winter months, offering vital additional protection and helping prevent avoidable deaths.

Who can get a Covid-19 booster jab?

Booster jabs are available to people over the age of 50, over-16s with health conditions that put them at higher risk of severe Covid-19, health and social care workers, adult carers, adults who live with someone with a weakened immune system, and homeless people.

They are currently only available via appointment rather than walk-in clinics.

The NHS will contact people eligible for booster jabs. This will be at least six months after your second dose of the vaccine.

If it has been six months and one week since your second dose, and you still have not been contacted, the NHS recommends using its online service to book your booster jab appointment.

Where to book your Covid-19 booster jab?

Booster jabs can be booked via the NHS website.

You can also call 119 (free) between 7am and 11pm, seven days a week, to book your appointment.

Where can you get your booster jab?

Booster jabs can be booked at large vaccination centres, pharmacies, or local NHS services such as your GP.

You'll be directed to where you can book your booster jab when the NHS contacts you.

What are third primary vaccines?

Third primary doses are used to improve the immune response to vaccination in people who might not have responded well to their first two doses.

It is available to people who had a severely weakened immune system at the time of their first two doses.

The main difference between the booster jab and third primary vaccine is that people eligible don't have to wait six months to get it and can get it quicker.

The NHS will send a letter to those eligible. You can find walk-in clinics delivering third primary doses via your local NHS health authority's website.

If you had already had a third booster you will not need a third primary dose.

If you are still yet to receive your first and second Covid vaccine doses, it is not too late.

Walk-in vaccine centres are operating across the UK.