R.J.
Vaccines don't ALWAYS work, or work perfectly.
- The immune system can toss the blueprint
- The illness could have mutated just enough that the antibody that's on file doesn't work and the body has to make a new one
- The immune system can be "slow"...aka you get a LITTLE bit sick, but a very very mild case. Because your immune system is already on it, just a little slow on the uptake.
- The blueprint can degrade over time (probably not the case here...but can happen with US as adults getting something twice, or something we've been vaccinated against)
So as to 'how bad it's going to get'...the best I've got for you is : it all depends. She could get a very very mild case, she could go all out. If your little one was vaccinated against it already she *probably* won't get it at all.
Make sure to give both of them a high fat + high protein diet (antibodies are fats and proteins...and the body is making gazillions of them at warp speed) & keep their fluids running high. (Low and behold, chicken noodle soup has all of the above).
Good Luck!!!