Over-65s are being advised to get a second booster dose of a Covid vaccine.
The National Immunisation Advisory Committee (Niac) is also recommending over-12s with a weak immune system should get their second booster.
People in these groups can book an appointment from today, as long as it has been four months since their first booster dose, or four months since they've tested positive for Covid-19.
Immunologist Dr Lara Dungan explained why people should sign up to get their fourth dose of a Covid jab.
"There may be vaccine fatigue out there in the community at the moment, but it's really important to remember that every different vaccine works in a different way and it works for a different length of time.
"There's evidence that the vaccine wanes after a certain length of time, so it is believed that this extra booster shot will really help to boost immunity and it should help to reduce the number of Covid cases."
