Physicians have a new option this year for vaccinating patients aged 65 and older against seasonal influenza, but vaccine experts can't say for sure whether it will keep more people from getting the flu, according to a recent report.
On Dec. 23, 2009, the Food and Drug Administration licensed Sanofi-Pasteur's Fluzone High-Dose vaccine, an injectable inactivated trivalent influenza vaccine that provides four times the amount of antigen contained in standard flu vaccines. The aim is to increase the immune response among older adults, who are at greater risk for hospitalization and death from seasonal influenza. The new vaccine will be available for the first time in the 2010–2011 flu season.
Immunogenicity data from prelicensure clinical trials showed that people aged 65 and older who received the high-dose vaccine had significantly higher hemagglutination inhibition titers against all three influenza virus strains, compared with the standard-dose Fluzone vaccine. While the higher immune response to vaccination generally correlates with protection against influenza, it is still unclear whether it will translate into fewer vaccine recipients getting the flu this year, according to the report (MMWR 2010;59:485–6).
People who received the high-dose Fluzone vaccine were also more likely to experience injection site reactions and systemic adverse events following vaccination. For example, in a study of 2,572 people who received Fluzone High-Dose and 1,275 who received standard-dose Fluzone, about 36% of high-dose vaccine recipients reported injection site pain in the week after receiving the vaccine, compared with 24% of standard dose vaccine recipients. However, the reactions were generally mild and didn't last long.
The Advisory Committee on Immunization Practices (ACIP), which advises the Department of Health and Human Services on vaccine-related issues, has not expressed a preference for whether the new high-dose vaccine should be used over existing vaccines in the 65 and older population. ACIP officials are awaiting postlicensure data that will show whether the vaccine actually offers greater protection against influenza illness for older people.
The results of a 3-year postlicensure study on Fluzone High-Dose, compared with standard-dose Fluzone, are expected sometime in 2012, the report said.