Hi mango tree,
Welcome to Cruisemates!
As CruiserEK said, keep your and your sweet baby's hands clean. Use hand sanitizers and wash your (and baby's) hands with soap often.
If there is an outbreak of norovirus you'll know, because you won't be able to serve yourselves in the buffet and there won't be salt and pepper shakers on the tables.
The norovirus is really not as "rampant" as you might think from reading posts. It's what (more year's ago than I'd like to remember!) was called the 24 hour stomach flu. If baby has uncontrolled vomiting or diarrhea (very unlikely), see the ship's doctor.
IMHO, I wouldn't worry too much about it! Have a wonderful cruise!