Quadrivalent Flu vaccine is designed to protect against four different flu viruses. Determining which strains will predominate during a season affects the overall efficacy of Influenza vaccine. If vaccines are produced with strains that are not prevalent during a flu season many more influenza cases will present that year.
Current trivalent vaccines help protect against 2 A strains but only 1 B strain. According to data from the Center for Disease Control, since 2001 trivalent influenza vaccines have not contained the predominately circulating B strain more than half the time. Often the B strains chosen in the vaccine are mismatched with the B strain circulating that year.
Quadrivalent influenza vaccine helps to mitigate exposure to two B strains thereby reducing exposure to the B strain that the trivalent vaccine has missed half the time.
NMS has several presentations of Quadrivalent Influenza vaccine available for the 2015 flu season.