What's a COVID booster vaccine?

Simply put, a COVID-19 booster is given at the end of a vaccination course completion and when immunity begins to reduce. For Pfizer/BioNTech and AstraZeneca, it’s the same dose as the original vaccine. For Moderna, it’s half the dose, as this has been shown to be just as effective.

For those who are identified as immunocompromised, through medication or condition, they will be offered a third dose of the original vaccine, and later a booster. They need this to achieve the same level of immunity and protection as everyone else.

While initial variants of COVID-19 responded well to the two jabs that make up "full vaccination", it was felt that immunity started to drop with time, and a booster gives the immune system that push back into high protection.

As the new variant, Omicron, came along, a booster plus the initial two jabs were shown to be much more effective against catching it or getting seriously ill from it, than just the two jabs alone. This has proved important as Omicron has become the dominant strain, and as it's much more contagious than previous variants.

Everyone over the age of 16 years old can get their booster dose, after they’ve completed their initial series of vaccinations. You can get your booster dose at least 3 months after your second dose of the vaccine (or third if you are immunocompromised).

Some children aged 12 to 15 are eligible for a booster dose if either they live with someone who has a weakened immune system or they have a condition that means they're at high risk of getting seriously ill from COVID-19.