Maybe she wouldn’t have gotten the flu if she stayed home, too.
The only way to not get the flu is to not ingest the virus into your system. Keeping your hands a face clean (Lysol wipes) and stay out of sick peoples’ faces is how you do this. Vitamin ABCD-XYZ is not going to save you from the flu. But, having a healthy immune system can shorten the duration by quickly “learning” to attack the virus. The only fail safe is the correct flu shot, and then only a week to ten days after receiving it.