> I really shudder to think how bad it would have been for her if she weren't vaccinated. I've heard this sentiment expressed by a number of people. How are y

> I really shudder to think how bad it would have been for her if she weren't vaccinated. I've heard this sentiment expressed by a number of people. How are you certain that the opposite couldn't have been true? How do you know, for instance, that the shots she took didn't happen to decrease her natural ability to fight off an infection?