DURHAM, NC — Which provides better protection for older adults: the adjuvanted inactivated influenza vaccine (aIIV) or high-dose inactivated influenza vaccine (HD-IIV)?
Both are U.S. Food and Drug Administration approved for adults older than 65. A study led by Duke University School of Medicine and the VA Durham, NC, Healthcare System compared serum hemagglutination inhibition (HAI) antibody titers for the A(H3N2) and A(H1N1)pdm09 and B strains after trivalent aIIV3 and trivalent HD-IIV3 in an older adult population. The Geriatric Research and Education Clinical Center (GRECC) at the Palo Alto, CA, VA Health Care System also participated in the study.
The results were published in the journal Immunity and Ageing.1
Included in the immunogenicity population were 342 participants who received aIIV3 and 338 participants who received HD-IIV3. “The proportion of participants that seroconverted to A(H3N2) vaccine strains after allV3 (112 participants [32.8%]) was inferior to the proportion of participants that seroconverted after HD-IIV3 (130 participants [38.5%]) at day 29 after vaccination (difference, – 5.8%; 95%CI, – 12.9% to 1.4%),” according to the researchers.
They reported no significant differences between the vaccine groups in percent seroconversion to A(H1N1)pdm09 or B vaccine strains, in percent seropositivity for any of the strains or in post-vaccination GMT for the A(H1N1)pdm09 strain, however.
The study noted that the geometric mean HI antibody titers (GMTs) for the post-vaccination A(H3N2) and B strains were higher after HD-IIV than after aIIV3.
“Overall immune responses were similar after aIIV3 and HD-IIV3,” the authors advised. “For the primary outcome, the aIIV3 seroconversion rate for H3N2 did not meet noninferiority criteria compared with HD-IIV3, but the HD-IIV3 seroconversion rate was not statistically superior to the aIIV3 seroconversion rate.”
- Schmader KE, Liu CK, Flannery B, Rountree W, et. al. Immunogenicity of adjuvanted versus high-dose inactivated influenza vaccines in older adults: a randomized clinical trial. Immun Ageing. 2023 Jul 1;20(1):30. doi: 10.1186/s12979-023-00355-7. PMID: 37393237; PMCID: PMC10314373. Vaccine
