Can probiotics be helpful in preventing the noro virus?

Probably not: While probiotics are helpful in prevention of bacterial gut infections, viruses are so small, they slip by a first line of defense--a healthy bacterial gut system. However, a study did show that preventative probiotics did shorten the course of fever (in an elderly group studied) when norovirus did hit them. Unfortunately, probiotics did not improve any other symptoms of gastroenteritis at all