Oscillococcinum is a good one to start with for the whole family, one twice daily for three days and then repeat in a week and then in a month, best equivalent to vaccination.
Others in order of preventative measures:
Immuplex 2 per day
TIM one or two per day
Chewable Congaplex for Kids one daily
In case of start of Flu like symptoms:
Immuplex- 4 every 3-4 hours the first day until no symptoms, reduce to 2 tmes daily for a week
Congaplex- Chewable for kids 3 every 4 hours until no symptoms
Flucomune- 3 three to 4 times like above
Unda #s 5, 15, 37 for kids, 5 drops three times daily in case of fever associated with the Flu like symptoms ( malaise, sore throat, sinus congestion, lung congestion, cough,....)
Under #s 5, 27, 220, if already in the lungs
Unda #s 2, 48, 710 if severe sinus congestion plus Pneumotrophin PMG 2 twice daily plus Digest forte one before each meal
Other supplement to consider to increase the dosage, since most everyone may already have at home; Oregano, Olive leaf, Abiotics, Intestinol, Garlic, GSE, Andrographis complex, Trifal, Vitamins (high doses of Zinc, D, C, A)
Last but not least Probiotic, at the beginning sign of any URI, high doses of probiotic by itself can be amazing protection against Flu bugs.