A third dose is a top up for those who may not have had a full immune response from the first two doses. The aim is to give you a similar level of protection as someone without a weakened immune system who has had two doses.
A booster is an extra dose to help people who have had two doses retain their immunity, maximising their protection against COVID-19 ahead of the tricky winter months.
Go to this page to find out more about our booster programme.
Rydym yn croesawu gohebiaeth a galwadau ffôn yn y Gymraeg neu'r Saesneg. Atebir gohebiaeth Gymraeg yn y Gymraeg, ac ni fydd hyn yn arwain at oedi. Mae’r dudalen hon ar gael yn Gymraeg drwy bwyso’r botwm ar y dde ar frig y dudalen.
We welcome correspondence and telephone calls in Welsh or English. Welsh language correspondence will be replied to in Welsh, and this will not lead to a delay. This page is available in Welsh by clicking ‘Cymraeg’ at the top right of this page.