In 1976, my university (University of Southern Mississippi) didn't give us a choice and didn't even ask questions about things like egg allergies, they just lined us all up in the sports hall and vaccinated us.
The flu shot probably won't do anything for a stomach virus, while most of us call that "the flu" as well; I learned when Nightwolf went to medical school that medically the flu viruses typically cause respiratory problems, fevers, headaches, but usually not violent nausea (although it can happen). The "Stomach Flu" is usually caused by a number of other viruses like the well-named "Winter Vomiting Bug," and also a number of types of milder food poisoning (milder in that you may wish you were dead but you don't usually die or even end up in the hospital), also medication reactions to things prescribed for flu symptoms or to prevent a bacterial infection (often done for older people or those with other medical conditions).
Antibiotics won't do a thing for the actual flu - or vomiting (often norovirus) but they can help stave off a bacterial lung infection in a person with an elderly or compromised immune system.