Not saying this about parent, but am absolutely saying it about the vaccine skeptic community in general.
If the barrier to asking a question is zero (i.e. someone without a high school biology education can ask a question and be listened to) but the barrier to answering any question to the community's satisfaction is high (i.e. a full study, on exactly that question, controlled for all variables, that shows a clear result) then the effort asymmetry leads to many unanswered questions.
... which the skeptic community then points to to support the belief that there are many legitimate unanswered questions.
"vapor trails" - well, if helps you sleep better.
You don't have to care about the people who aren't interested in science. Sure, you have to protect immunocompromised people from those people, and we can do that.