Putting aside for one moment any issues surrounding the safety or need for vaccination, many parents do vaccinate their children. Many people choose, and are advised, to take a painkiller before a vaccination to minimise after-effects. New research shows this may be the wrong thing to do. When immune cells were exposed to over-the-counter painkillers paracetamol, aspirin and ibuprofen, their ability to produce antibodies was diluted. This is probably because the pain-killing action of these drugs is due in part to reducing the action of an enzyme called cox-2. This is not a good idea in the context of vaccination, however, because the cox-2 enzyme is necessary for the optimal production of B-lymphocytes, the immune cells that produce antibodies.
Source: Cellular Immunology
Source: Cellular Immunology