10 month old baby at risk for having measles from the Disneyland outbreak, puts his 3 year old siste

[Riutet]

I don't see how you can become a doctor without knowing how vaccines work and that they aren't necessarily harmful.

If you have anything approaching an understanding of how the immune system works you'll also likely have learned how vaccination works. Even if you learned how the immune system works but not how vaccines work you will at least be able to reason that having an attenuated antigen introduced into your system would allow your body to develop immunity without putting you at any risk.

If you don't know how the immune system works even on the most basic level, how do you get to become a doctor?