Influenza vaccines are designed to protect against the influenza virus, which causes the flu. These vaccines work by stimulating the immune system to recognize and fight the virus, reducing the risk of illness. They are typically updated each year to match the most common strains of the virus circulating in the population. There are different types of influenza vaccines, including inactivated vaccines, which contain killed virus, and live attenuated vaccines, which contain weakened virus. Vaccination is recommended for most people, especially those at higher risk, such as the elderly, young children, and individuals with certain health conditions.