Question: How exactly are vaccines developed?

Alena Pance answered on 1 Jun 2020:

Hi Jack,
There are different types of vaccines. Some consist in a pthogen that is killed, inactived or mushed up and injected into people. Other vaccines consists in a protein from the pathogen, which is accessible to the immune system and important to the infection. This is a bit more difficult because a lot of research is invested into identifying this molecule on the surface to the pathogen, be it a bacteria, a virus or a complex parasite. It needs to be ensured that this molecule is unique to the pathogen and it usually needs to be in a solution that is able to induce the immune system. It is also necessary to find out whether the molecule of choice varies a lot in the population of pathogens, because if it does, then the immune system will be able to recognise and react against the pathogens that carry specifically that molecule but will not be effective against pathogens that carry a different version of the molecule. A good example is malaria, the parasite is quite different in different geographic regions and so a vaccine made with molecules from one of the laboratory parasites is not necessarily effective when used in different parts of the world.
Either way, the ides is to induce the immune system of people to recognise the pathogen to generate specific antibodies and cells that will be able to interfere with the infection, inactivate and kill the pathogen and eliminate it from the body.