FDA clears first quadrivalent flu vaccine

Mar 1, 2012 (CIDRAP News) – The US Food and Drug Administration (FDA) yesterday approved the first quadrivalent influenza vaccine, an inhaled live attenuated influenza vaccine developed by MedImmune and modeled after its FluMist product.

The vaccine includes a second influenza B strain, which is designed to broaden protection against circulating strains. MedImmune plans to have the quadrivalent vaccine ready for the 2013-14 flu season.

Flu experts often have a difficult time deciding which lineage—Yamagata or Victoria— to suggest in their annual vaccine recommendations, because influenza B circulation is so unpredictable.

For example, vaccines for this season's Northern Hemisphere trivalent flu vaccine include a Victoria lineage influenza B strain. Few influenza B viruses have been available this season for testing by the Centers for Disease Control and Prevention (CDC), but about half are of the Yamagata strain that's not covered by the current vaccine.

Karen Midthun, MD, director of the FDA's Center for Biologics Evaluation and Research, said in a press release that the influenza B burden is greatest in children, particularly preschoolers and school-aged youngsters. "A vaccine containing the four virus strains most likely to spread and cause illness during the influenza season offers an additional option to aid in influenza prevention efforts," she said.

The FDA said the safety and effectiveness of the quadrivalent vaccine is supported in earlier FluMist trials, along with three new clinical studies on the quadrivalent version that involved 4,000 adults and children. It added that the studies suggested immune responses and adverse reactions were similar for both vaccines.

For the trivalent version of FluMist, a meta-analysis last fall found a pooled efficacy of 83% in children 6 months to 7 years but no significant efficacy in randomized control trials in older children or adults.

MedImmune submitted its licensing application for the quadrivalent flu vaccine, indicated for use in people ages 2 through 49, in the second quarter of 2011.

Yesterday's approval followed an FDA advisory committee's recommendation for the flu strains to include in the 2012-13 flu vaccine, which for the first time included recommendation for a second influenza B strain, if a quadrivalent flu vaccine is available.

During a meeting of the Vaccines and Related Biological Products Advisory Committee (VRBPAC) this week, some members referred to the difficulty of selecting one influenza B strain for the trivalent vaccine as a "crapshoot" and a "coin flip."

Stan Block, MD, professor of clinical pediatrics at the University of Kentucky College of Medicine in Lexington, said in a MedImmune press release yesterday that according to CDC data, both influenza B strain lineages have circulated since the 2001-02 season. He said that in half of the flu seasons since then, the predominant influenza B lineage was different than the one included in the vaccine.

Though the vaccine is designed to provide protection against a broader range of flu strains, MedImmune pointed out that the quadrivalent vaccine may not prevent influenza in everyone who is immunized.

Tor Constantino, MBA, MedImmune's director of product public relations, told CIDRAP News that the quadrivalent vaccine won't be available for the 2012-13 flu season, but it expects to have it available for the 2013-14 season.

MedImmune is awaiting a recommendation from the CDC's Advisory Committee on Immunization Practices (ACIP), the group that develops guidelines for vaccinate usage. Constantino said a routine ACIP recommendation would support payer acceptance and physician uptake.

If the ACIP makes a recommendation about the quadrivalent vaccine, MedImmune would convert all available US doses to the new formulation beginning in 2013 when the product is available, he said. A trivalent version, however, will still be made and available outside the United States.

Constantino said since more steps are needed to launch the vaccine in the United States, it's too early to detail plans to submit licensing applications for the quadrivalent vaccine in other countries, but he added that MedImmune does plan to make a regulatory filing in the European Union later this year.

Other flu companies are developing quadrivalent flu vaccines, as well. At the VRBPAC meeting, an official from GlaxoSmithKline said its vaccine had gone through clinical trials, but it didn't anticipate clearance in time for the 2012-13 season.

See also:

Feb 29 FDA press release

Feb 29 MedImmune press release

Feb 28 CIDRAP News story "FDA picks two new vaccine strains for the 2012-13 flu season"

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