[ProspectiveSingleMom]

I think I'm confused. Are we talking about children who are as-yet unvaccinated (i.e. haven't gotten to the age for a specific vaccine or finished the series yet) being exposed to illness? In those cases then you'd want to know if a child is exposed to a carrier, which is why outbreaks get media coverage and anyone who was known to have had contact with an infected individual is directly notified. If the vaccine works, you shouldn't have to worry, and if you are concerned, you should request a titer. I've had titers for hep. B and MMR and know that I am immune to all, so I would and do feel 100% comfortable coming into contact with someone who has any of those illnesses (though of course use precautions to prevented spreading to others who may not be immune).