Betty65, diseases can be caused by bacteria or viruses. Whooping Cough is caused by a bacterium, but other diseases that we routinely vaccinate against, such as measles and rubella (German Measles), are caused by viruses, as is Chicken Pox. My brother, born in the early 1960s, was vaccinated against Measles as a small child when the vaccination was still being evacuated in the UK. Every year afterwards, until he reached his teens, our parents received a questionnaire, asking if he had become infected with it. The year after they stopped asking - he got Measles! No vaccine gives 100% immunity. I had a friend whose child caught Whooping Cough although he had received the vaccination, for example, but he scarcely whooped, making it very difficult to diagnose. Even in the early days of the Covid vaccination roll-out, they warned that it would not give total immunity to everyone who had it, but would reduce its severity and they were right. Yes, there were some very rare unforeseen side effects, but these were so uncommon that they would probably never have shown up until scaled up to millions of people receiving them because they have been so vanishingly rare statistically. When any have been observed, steps have been taken to use different vaccines with those who might be affected. Plus, however bad the more common side effects (I felt quite fluey after the first one), how much worse would people have been with the full infection and no protective vaccination?