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An Optimized Hemagglutination Inhibition (HI) Assay to Quantify Influenza-specific Antibody Titers
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An Optimized Hemagglutination Inhibition (HI) Assay to Quantify Influenza-specific Antibody Titers

Published on: December 1, 2017

Comparison of one- and two-dose regimens of influenza vaccine for elderly men

M Levine1, B L Beattie, D M McLean

  • 1Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver.

CMAJ : Canadian Medical Association Journal = Journal De L'Association Medicale Canadienne
|October 15, 1987
PubMed

Insights

A second dose of trivalent inactivated whole-virion influenza vaccine did not improve immune response in elderly men. Many older adults remained unprotected against influenza during the season.

Area of Science:

  • Gerontology
  • Immunology
  • Vaccinology

Background:

  • Elderly individuals, particularly those in long-term care facilities, are at high risk for influenza complications.
  • Assessing the efficacy of influenza vaccination strategies in this population is crucial for public health.

Purpose of the Study:

  • To evaluate the immunogenicity of a two-dose regimen of trivalent inactivated whole-virion influenza vaccine in elderly men residing in a long-term care facility.
  • To determine if a second vaccine dose administered 8 weeks after the first enhances the antibody response.

Main Methods:

  • 102 male residents (mean age 74.6 years) received one dose of trivalent influenza vaccine; 55 received a second dose 8 weeks later.
  • Serum samples were collected pre-vaccination and at 4, 8, 12, and 16 weeks post-first dose.
  • Hemagglutinin-inhibiting (HAI) antibody titers to A/Philippines/2/82 (H3N2), A/Chile/83 (H1N1), and B/USSR/83 were measured.

Main Results:

  • Both groups showed significant increases in HAI antibody titers 8 weeks after the first dose (p < 0.05), except for the B/USSR antigen.
  • No significant differences in seroconversion rates, geometric mean titers, or proportion of subjects with HAI titers ≥ 1:40 were observed between the one-dose and two-dose groups at 8 or 16 weeks.
  • At 16 weeks, HAI titers ≥ 1:40 were achieved by 60% for A/Philippines, 32% for A/Chile, and 13% for B/USSR antigens.

Conclusions:

  • A second dose of this influenza vaccine, given 8 weeks after the first, does not appear to enhance the immune response in elderly men.
  • A significant proportion of elderly men in long-term care facilities may remain susceptible to influenza infection due to inadequate antibody titers (< 1:40) during the season.

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