Rav Nahman was suspicious of the medical profession. See the Conversations of Rav Nahman perek 50. So just based on that, I think it is best to not to take cures or "vaccines" if you are not sick. And even when something is wrong, one needs to be careful. At least I noticed in Uman that doctors were very careful to never try new experimental stuff. But elsewhere, I would refrain from doctors. They just have too many new toys that they are just dying to try out on us.