Influvac is a brand of influenza vaccine used to protect against infection by influenza viruses. It is formulated to match the strains of the virus that are predicted to be the most common during the upcoming flu season, including both Influenza A and B types. The vaccine works by stimulating the body's immune system to produce antibodies against the influenza virus, thereby providing immunity or reducing the severity of the illness if the vaccinated individual is exposed to the virus. Influvac is typically administered as an injection into the muscle and is recommended for annual vaccination in individuals who are at risk of severe complications from influenza, as well as anyone looking to reduce their risk of contracting the flu. The specific composition of Influvac may vary from year to year based on the World Health Organization's recommendations.