Under the National Immunisation Program (NIP), free influenza (flu) vaccine is offered to children between 6 months and under 5 years of age to protect them and the wider community from flu. Infants and young children are most likely to spread the flu and suffer complications. The vaccine is available from your usual immunisation provider. Children under 9 years of age require 2 doses at least 4 weeks apart in the first year of flu vaccination.