The other poster made a statement about the strength of the immune system. I don't think there's much evidence that exposure to virus A ends up contributing to a robust response to virus Z. There's some benefit if the infections are somewhat related, but not if they are dissimilar. So sure, exposure to a particular infection is likely to make your immune system more responsive to that infection, but it's probably not reasonable to say that it has gotten stronger.

And then, measles in particular can actually damage existing immunity to other infections, making exposure to it quite a lot more dangerous than just the immediate infection. https://asm.org/articles/2019/may/measles-and-immune-amnesia