and i've heard that if they get exposed to lots of colds when they are at a young age, their immune system is strengthened and they dont get as much colds later on in life
my dr says the exact same thing.

I've heard that once cold or flu symptoms disappear, you don't really get over the cold for up to another 2 weeks.
I find the best thing is to reguarly clean all Nina's toys to rid of any germs.