High-Dose Flu Vaccine
On December 23, 2009 the U.S. Food and Drug Administration (FDA) approved the high-dose influenza vaccine (HDV) for use in persons 65 years of age and older.
The brand name of the vaccine is Fluzone High-DoseTM and its manufacturer is Sanofi-Pasteur. The vaccine is given as a single injection in the arm like the standard flu shot, but it contains four times the antigen dose of the standard-dose flu vaccine (SDV). HDV will be available to patients 65 and older in provider offices at PAMF and at a limited number of weekday flu clinics for the 2012/2013 flu vaccination season – see our website for details.
Q: Why was the HDV for seniors developed?
A: Persons 65 and older have the highest rates of death from the flu (with exception of the 2009 H1N1 pandemic flu, which took a greater toll on younger persons), yet the current SDV only provides partial immunity against the flu in the elderly. Researchers are exploring a variety of ways to boost the immune response in seniors against the flu, and an HDV is one of them.
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Q: Is there evidence that the HDV provides better immunity than the SDV against the flu in seniors?
A: The largest study to date compared the HDV to the SDV in approximately 4000 persons 65 and older during the 2006-2007 flu season (Journal of Infectious Diseases, 2009; 200:172-180). This randomized, controlled trial demonstrated higher antibody levels for the A (H3N2) and A (H1N1) flu strains, and about the same level of antibodies for the B strain when the HDV was used. Although encouraging, this study has some limitations:
- Rates of infection, illness and death from the flu were not examined. (It is not yet known if the HDV is more clinically effective in seniors than the SDV.)
- The duration of higher antibody levels was not measured. (Flu can sometimes peak late in March as it did last season, long after flu vaccines are given in the fall. Waning antibody levels may also be a problem with the SDV.)
- Patients included in the study were medically stable persons living in the community. (The vaccine’s performance in seniors with many medical problems or in long-term care facilities is not known.)
- Potential adverse effects of the vaccine may not appear until many persons have been vaccinated. (The 4000 persons in the study is a relatively small number.)
- Research results on the clinical effectiveness of the HDV are not expected to be available until the 2014-2015 season.
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Q: Is the HDV safe?
A: The study cited above suggests that side effects from the HDV are slightly more common than with the SDV. For example, pain at the injection site and fever above 100.4 degrees were both more common with the HDV vs. the SDV (36 versus 24 percent, and 1.1 versus 0.3 percent, respectively). As noted, the HDV has not yet been given to large numbers of patients. The manufacturer and public health researchers will be observing closely for any new side effects that may appear as the vaccine goes into widespread use. A recent study showed no strong trend in major adverse events associated with the HDV although gastrointestinal symptoms seemed to be more common (Moro P et al. Postlicensure safety surveillance for high-dose trivalent inactivated vaccine in the Vaccine Adverse Event Reporting System, 1 July-31 December 2010. Clin Infect Dis 2012; 54:1608-14).
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Q: I am a senior. Should I get the new HDV?
A: The Advisory Committee on Immunization Practices for the U.S. Centers for Diseases Control and Prevention has not expressed a preference for either the HDV or the SDV for those 65 or older. The HDV will be available in provider offices and in some flu clinics (check the