Fluzone High-Dose Foils Flu Better in Seniors, Says Maker

October 24, 2013

Fluzone High-Dose was 24.2% more effective in preventing influenza in adults aged 65 years or older than regular Fluzone in a large-scale clinical trial, vaccine maker Sanofi Pasteur told the Advisory Committee on Immunization Practices (ACIP) of the Centers for Disease Control and Prevention today.

Sanofi Pasteur developed Fluzone High-Dose, which delivers 4 times the antigen dose found in Fluzone, because regular influenza vaccines generally are less effective in preventing illness among the elderly than among younger adults. The US Food and Drug Administration (FDA) approved Fluzone High-Dose in December 2009 on the basis of clinical studies showing that it triggered a stronger immune response than Fluzone to influenza A(H1N1) and A(H3N2) and proved "non-inferior" when it came to influenza Type B.

There were no clinical studies at the time of approval, however, demonstrating that the vaccine outperformed Fluzone in actually preventing cases of influenza or its complications in the elderly. As part of the vaccine's approval, the FDA required Sanofi Pasteur to conduct such a confirmatory study, which it did. David Greenberg, MD, the company's vice president of US scientific and medical affairs, presented the results at the ACIP meeting today in Atlanta, Georgia.

Dr. Greenberg told the committee that uptake of Fluzone High-Dose among the elderly has been limited so far because healthcare providers and advisory groups were waiting to see the numbers from the postapproval efficacy study. Last year, he said, only 20% of vaccinated seniors had received Fluzone High-Dose.

The clinical trial encompassed 32,000 adults aged 65 of years or older in the United States and Canada and spanned both the 2011-2012 and 2012-2013 influenza seasons. Participants were randomly assigned to receive either Fluzone or Fluzone High-Dose and monitored for illness until the end of each season.

The rate of laboratory-confirmed influenza among participants receiving Fluzone High-Dose was 1.43% compared with 1.89% among patients immunized with Fluzone. For the FDA to deem Fluzone High-Dose as superior, the vaccine needed to demonstrate a relative efficacy rate of at least 9.1%. It achieved a rate more than twice that — 24.2%. Dr. Greenberg noted that the clinical superiority of Fluzone High-Dose held true across different age groups of the elderly, influenza types, different definitions of influenzalike illness, and individual influenza seasons.

"This is an extremely important landmark study," Dr. Greenberg told the committee, "because it proves once and for all that Fluzone High-Dose provides a clinical benefit that is superior compared to Fluzone in reducing the incidence of…influenza in this highly vulnerable population."

Participants immunized with Fluzone High-Dose experienced serious adverse events and death at rates almost identical to those for the group receiving Fluzone.

Dr. Greenberg said that his company would submit a report on the efficacy study to the FDA by the first quarter of 2014 as well as revised label language for Fluzone High-Dose that will include study findings.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.