said it is still "unclear" whether all over 50s should be offered a third jab this autumn. our health correspondentjim reed explained why a third booster had been suggested. there are two reasons why scientists and politicians might want to go ahead with this. one is to top up immunity. there are some early signs in some research that, over time, the immunity you gain from taking a vaccine might fade although at the moment research in that is ongoing. the second main reason is the potential emergence of new variants of the virus this autumn and, again, a third booster dose might offer some extra protection against that. yesterday the health secretary for england, sajid javid, was asked about this, and he suggested the plan would probably be all over 50s would be offered a booster shot at the same time as their flu shot this autumn. but before going ahead, politicians in every part of the uk, every nation, are waiting on advice,