Every year in the United States, around 20 percent of the population gets the flu. The Centers for Disease Control and Prevention (CDC) recommends the annual flu vaccine for everyone over the age of 6 months, unless the vaccination is deemed unsafe due to medical conditions, and generally about half of people do.
The currently licensed flu vaccines in the U.S. are live-attenuated influenza vaccines (LAIV), recombinant hemagglutinin (HA) vaccines, and inactivated vaccines (including whole inactivated vaccines, split vaccines, and subunit vaccines). The last group, inactivated influenza vaccines, are the most commonly used. Every year, several months before the annual flu season starts, the Food and Drug Administration (FDA) decides which four strains of the seasonal flu virus will be dominant and informs the vaccine manufacturers accordingly….