... Norovirus is A: A virus, so anti-boitics would have negligible effect on them and B: Norovirus isn't vaccinated against.
Norovirus is a food borne illness that can pass person to person once ingested. You can prevent it by being cautious about food safety. If you're worried about it, look up your food safety and follow it religiously. In fact, normal norovirus accounts for the largest percent of foodborne illness. However it is much less dangerous than Salmonella, e. coli and most other foodborne illnesses. I just learned about this stuff during last semester, so these anti-vaxxers are so far off that they need to be slapped. Lots.
Also, surprised the 'raw' foodies aren't out.