The three Covid-19 vaccines are from Pfizer-BioNTech, the University of Oxford and Astra-Zeneca and Moderna.
The Pfizer, Oxford and Moderna vaccines each require two doses and you are not fully vaccinated until you’ve had both shots.
But there are many differences between them.
BBC health correspondent Laura Foster looks at how much immunity they give, how they prevent infection and how they compare.
Video by Mel Lou, Laura Foster, Terry Saunders and Mattea Bubalo.