The quadrivalent influenza vaccine is designed to protect against four different strains of the influenza virus. It includes two strains of influenza A and two strains of influenza B, providing broader coverage compared to trivalent vaccines, which only target three strains. This vaccine is typically administered annually to help reduce the risk of flu during the peak season. The quadrivalent vaccine is available in various forms, including injections and nasal sprays. It is recommended for individuals aged six months and older, making it suitable for a wide range of people. Vaccination helps to lower the chances of severe illness, hospitalization, and complications associated with the flu.