• micronutrients;
  • long-term care;
  • elderly;
  • influenza vaccine;
  • antibody response

Objectives: To test the hypothesis that a micronutrient supplement can improve seroconversion after influenza immunization in older institutionalized people.

Design: Randomized, double-blind, placebo-controlled study.

Setting: Nursing and residential homes in Liverpool, United Kingdom.

Participants: One hundred sixty-four residents aged 60 and older from 31 homes were initially randomized; of these, 119 (72.6%) completed the study.

Intervention: Participants were randomized to receive a micronutrient supplement providing the reference nutrient intake for all vitamins and trace elements or identical placebo. Tablets were taken over an 8-week period during September and October 2000; influenza vaccine was administered 4 weeks after their commencement.

Measurements: The hemagglutination-inhibiting antibody response as defined by a fourfold or greater titer rise over 4 weeks and assessed separately for each of the three antigens contained in the 2000/2001 influenza vaccine (A/New Caledonia/20/99 (H1N1), A/Moscow/10/99 (H3N2), B/Beijing/184/93 (B)).

Results: Despite a significant increase in serum concentrations of vitamins A, C, D3, E, folate, and selenium in the supplemented group, there was no significant difference between groups (supplemented vs placebo, respectively) in the proportion of participants seroconverting to H1N1 (41% vs 49%, P=.374), H3N2 (49% vs 58%, P=.343), or B (41% vs 40%, P=.944).

Conclusion: A micronutrient supplement providing the reference nutrient intake administered over 8 weeks had no beneficial effect on antibody response to influenza vaccine in older people living in long-term care.