It would be difficult to give people the whole cells. We can however use the antibodies to give someone passive (temporary) immunity. An example is this is when people are exposed to rabies and they have not been vaccinated before, we give them antibodies to rabies to try and neutralise the virus.
We’re trying to! However, as one of my colleagues bluntly put it, ‘it’s a bit like looking for a needle in a haystack’. Two quite extreme ways of doing it are via bone marrow transplants and gene therapy – not great for everyday use! In flu and HIV, scientists are trying to identify people with really good antibodies. The idea is then to make a matching antigen for that antibody to put in a vaccine – when someone gets vaccinated, their immune system should then learn how to make the good antibodies, ready for when they might get infected.
As Hannah says, we can already treat people with ‘manufactured’ antibodies – but these only give temporary immunity. Another example where antibodies can be used in this way is rheumatoid arthritis.