Efficacy of High Dose Influenza Vaccine in the Elderly

As seen in the Consultant Connection February 2015 Issue
In the 1990s, influenza infection caused an average of 36,000 deaths and 226,000 hospitalizations annually. The majority of hospitalizations and deaths occurred in people aged 65 years or older. Clearly, the elderly are especially vulnerable to flu and flu-related complications, but their antibody response after immunization is less robust than that in younger adults. Since December 2009, a high-dose trivalent flu vaccine formulation has been FDA-approved. It contains four times more hemagglutinin per dose than a standard flu vaccine and should provoke a stronger antibody production. It has also been associated with more injection-site reactions and costs more than standard influenza vaccine.
In August, 2014 The New England Journal of Medicine published a head-to-head comparison of high-dose and standard-dose trivalent vaccine in seniors to determine if higher antibody levels protect against the flu better. This study enrolled roughly 32,000 adults 65 years and older from 126 research centers in the United States and Canada. They assessed protection from vaccination during two flu seasons:
  • The 2011-2012 flu season, which had low influenza activity with moderate to good match between vaccine and circulating strains; and
  • The 2012-2013 season, which had high influenza activity and a mismatch between vaccine and circulating strains.

The researchers randomized seniors to high-dose trivalent or standard-dose trivalent flu vaccine. They drew blood hemagglutinin inhibition titers one month after immunization. Seniors who received the high-dose vaccine had significantly higher antibody responses than those who received standard flu vaccine. Among seniors who received the high-dose vaccine, 228 individuals developed laboratory-confirmed influenza compared to 301 receiving standard-dose trivalent vaccine, suggesting that high dose vaccine was 24.2% more effective in preventing flu compared to standard dose vaccine (95% CI 9.7-36.5).
The researchers conclude that seniors who receive high-dose trivalent flu vaccine have more robust antibody responses and are better protected against the flu compared to those receiving standard trivalent vaccine. This study only involved trivalent preparations; no comparison was made to quadrivalent flu vaccination formulations.
Please note that the CDC’s Advisory Committee on Immunization Practices has not reviewed this information nor have they adopted this finding as a recommendation at this time.
The CDC has a web page devoted to high-dose influenza vaccine: http://www.cdc.gov/flu/protect/vaccine/qa_fluzone.htm
Reference: DiazGranados CA, Dunning AJ, Kimmel M, et al. Efficacy of high-dose versus standard-dose influenza vaccine in older adults. N Engl J Med. 2014;371:635-45.

Back to Articles