FDA approves first quadrivalent flu vaccine

FDA approved the first 4-strain influenza vaccine live, intranasal (FluMist Quadrivalent, MedImmune) for the prevention of influenza. According to MedImmune, all other licensed seasonal influenza vaccines are trivalent, containing 3 strains (2 strains of type-A influenza [A/H1N1 and A/H3N2] and 1 B strain). FluMist Quadrivalent contains 4 strains (2 type-A and 2 type-B lineages) to help provide broad protection against circulating influenza A and B.

The ability to add another strain of influenza B without compromising the vaccine’s ability to protect against the other 3 strains will allow scientists to make a better vaccine, according to Robert Belshe, MD, director of Saint Louis University’s (SLU) Center for Vaccine Development and professor of infectious diseases. SLU conducted the research on the quadrivalent vaccine.

“The intent with the trivalent is to take care of all flu,” Belshe said. “But in reality we have to guess right and put the right strains in the vaccine. We weren’t very good at guessing which strain of B to use. The A and B strains still change, so we have to keep up with that change. Adding the second B strain will certainly help on the B side and be more likely to protect.”

The nasal spray vaccine was tested in approximately 2,300 children between 2 and 19 years of age. The children were randomly assigned to receive 1 of 3 vaccines: a vaccine containing 4 strains of influenza – 2 of influenza A and 2 of influenza B, or 1 of 2 vaccines that contained both influenza A strains and 1 of each of the influenza B strains. Researchers looked at the safety and antibody response to both influenza A and B viruses in the children of different age groups who were vaccinated. The children who received vaccine containing 4 strains of flu had as robust of an immune response as those who received the vaccine that contained 3 strains.

The vaccine could be ready for use during the 2013-2014 influenza season, pending a recommendation from the Advisory Committee on Immunization Practices, a group that advises the Centers for Disease Control and Prevention about vaccination issues.

“I expect in the not-too-distant future we’ll see approval of flu shots with 4 strains,” Belshe said.