Just to go a little further on that from a quick glance at the link Adam posted it doesn't seem that the GP personally is remunerated for giving a jab but the surgery/practice. Whether they then just divvy it up and take it home I don't know but chances are some of them will invest that back into the surgery to buy new equipment, carry out renovations, buy better PPE for their staff etc. It doesn't seem to be quite as clear cut as GPs running round singing 'We're in the money'...