I too would not trust scientists if I had never read any books about how deadly life was before antibiotics, vaccinations, sanitation, and other public safety campaigns.
Somehow we're ok with modern science eradicating a ton of diseases (including stuff you wouldn't think about at first, like getting rid of tapeworm in pork), reducing infant mortality (which has positive repercussions throughout all of society), changing HIV from a death sentence to just a chronic condition (oh, we have a cure for hep C too, by the way), and so on, most of which involve trusting scientists to give or inject something that could potentially cause a little bit of harm (which is a fair concern for someone with a compromised immune system but for most healthy adults is the equivalent of crying about getting poked with a needle for a blood draw). But ask someone to engage their immune system by breathing in some harmless dead viral particles, a technique that has been used for hundreds of years, that's too much.
