Can a short period of micronutrient supplementation in older institutionalized people improve response to influenza vaccine? A randomized, controlled trial.

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.

Difficulties of recruitment for a randomized controlled trial involving influenza vaccination in healthy older people.

BACKGROUND: In a randomized controlled trial to determine the cost benefits of influenza vaccination in fit healthy individuals aged 65-74 years, recruiting individuals to the study was more difficult than anticipated. OBJECTIVES: To investigate reasons for poor recruitment. MATERIALS AND METHODS: 6,058 people were initially identified as eligible for the study but only 729 (12%) were subsequently randomized. Individuals (n = 2,583) who returned cards indicating that they did not wish to participate were sent a postal questionnaire asking for reasons why they felt unable to consent for the study. RESULTS: 1,173/2,583 (45.4%) questionnaires were returned. A total of 2,621 reasons were given for nonparticipation, i.e. a mean of 2.2 reasons per questionnaire returned. Reasons given for noninvolvement were: reluctance to participate in a research project (53%); concerned about side effects (34%); self-perceived view of not requiring influenza vaccination (31.7%); preference for own doctor to give the vaccine (29.1%); objection to name "Geriatric Medicine" on the letter of invitation (25.2%); already been vaccinated (17.3%); illness requiring vaccination out of the study (13.8%); previous bad reaction to the vaccine (6.4%); unable to attend on day of vaccination (4.3%); unable to get to general practice surgery (4%); already involved in a clinical trial (2.5%); fear of needles/dislike of injections (1.6%); doubts about vaccine efficacy (0.3%); egg allergy (0.2%). CONCLUSION: Inaccurate beliefs about influenza vaccination persist across a wide section of the community. Efforts should be made by all health professionals to correct these false beliefs and ensure that those at risk can be easily recognized and targeted for vaccination.