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

Gerontology. May-Jun 2002;48(3):170-3. doi: 10.1159/000052837.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Data Collection
  • Humans
  • Influenza Vaccines / administration & dosage*
  • Patient Selection*
  • Randomized Controlled Trials as Topic*
  • Surveys and Questionnaires
  • Treatment Refusal
  • Vaccination*


  • Influenza Vaccines