High-Dose Vaccine May Improve Influenza Protection in Elderly

Lara C. Pullen, PhD

December 19, 2014

Frail, elderly residents of long-term-care facilities (LTCFs) who received the high-dose inactivated influenza vaccine (HD IVV) during the 2011 to 2012 and 2012 to 2013 influenza seasons produced more robust immune responses to all strains of influenza when compared with residents who received standard-dose IVV. The only exception was response to influenza strain A(H1N1), for which noninferiority criteria were met.

David A. Nace, MD, MPH, from the University of Pittsburgh in Pennsylvania, and colleagues published their single-blinded, randomized, controlled trial online December 17 in the Journal of Infectious Diseases. They recruited 205 patients (from multiple LTCFs; a total of 187 individuals completed the study. Subjects were 85 years old or older and had a mean age of 86.7 years.

The investigators evaluated the efficacy of the HD IVV that was approved in the United States in 2009 and compared it with the efficacy of standard dose IVV. They measured geometric mean titers and seroconversion rates at day 30 and day 180 postvaccination. The study did not examine clinical disease.

In addition to producing superior antibody responses, the investigators found that the antibody titers in response to HD IVV remained elevated between day 30 and day 180.

"The very frail elderly are vulnerable to severe complications from influenza, and we have been clamoring for a more protective vaccine for the elderly for a while. This study, coupled with the recent effectiveness study published in [the New England Journal of Medicine], suggests that we now have one. It would be inappropriate that we do not use it in that population," explained Litjen Tan, PhD, from the Immunization Action Coalition in St. Paul, Minnesota, to Medscape Medical News.

Dr Tan emphasized that although Medicare covers the HD vaccine, it is important for physicians to seize all opportunities to vaccinate. Vaccinations should not be delayed if HD vaccine is not in stock.

Study Limitations

In an accompanying editorial, Megan C. Lindley, MPH, and Carolyn B. Bridges, MD, from the Centers for Disease Control and Prevention in Atlanta, Georgia, emphasize that the study included serum titers and not clinical outcomes. They thus expressed the need for additional research.

"Nace et al note several potential challenges to conducting a clinical trial among LTCF residents to examine the clinical benefit of HD versus standard-dose influenza vaccination to prevent influenza and its complications. However, several cluster-randomized trials in LTCFs that included influenza surveillance among LTCF residents have been successfully conducted to study the effects of [healthcare personnel] influenza vaccination on LTCF residents. Similar trials focused on vaccination of LTCF residents would provide much-needed information about the relative benefits of HD versus standard-dose vaccine for preventing influenza in this frail group," they write.

Dr Tan agreed that the measured immune responses are not necessarily going to translate into clinical efficacy.

"Serological outcomes do not always translate into clinical efficacy. However, we do have [the New England Journal of Medicine] paper showing about a 25% efficacy in reducing first incidence of influenza, and the serological readouts are comparable," he explained. The other study focused, however, on individuals who were 65 years of age or older, as opposed to the frail subjects of the current study.

The research was supported, in part, by Sanofi Pasteur. Dr Tan has received honoraria from Pfizer, Merck, Novartis, Temptime Corp, and TruMedSystems for service as a scientific consultant. Two coauthors have received research grants from Pfizer, Merck, and Sanofi Pasteur. One coauthor consults for MedImmune. One coauthor is funded by Sanofi Pasteur to develop a universal influenza vaccine. The other authors, Dr Lindley, and Dr Bridges have disclosed no relevant financial relationships.

J Infect Dis. Published online December 17, 2014. Article full text, Editorial extract

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