Intended for healthcare professionals


Multiple vaccinations, health, and recall bias within UK armed forces deployed to Iraq: cohort study

BMJ 2008; 337 doi: (Published 30 June 2008) Cite this as: BMJ 2008;337:a220
  1. Dominic Murphy, research worker ,
  2. Matthew Hotopf, professor of general hospital psychiatry,
  3. Simon Wessely, professor of epidemiology and liaison psychiatry
  1. 1King’s Centre for Military Health Research, King’s College London SE5 9RJ
  1. Correspondence to: D Murphy dominic.murphy{at}
  • Accepted 5 May 2008


Objective To assess the relation between self reported number of vaccinations received and health, and between numbers of vaccinations recorded from individuals’ medical records and health.

Design First phase of a cohort study.

Setting UK armed forces personnel.

Participants 4882 randomly selected military personnel deployed to Iraq since 2003 and a subset of 378 whose vaccination records were accessed.

Main outcome measures Psychological distress, fatigue, symptoms of post-traumatic stress disorder, health perception, and multiple physical symptoms.

Results Personnel who reported receiving two or more vaccinations on a single day were more likely to report symptoms of fatigue (adjusted risk ratio 1.17, 95% confidence interval 1.05 to 1.30), show caseness according to the general health questionnaire (1.31, 1.13 to 1.53), and have multiple physical symptoms (1.32, 1.08 to 1.60). These associations were no longer significant when number of vaccinations recorded in individuals’ medical records was used as the independent variable.

Conclusions Multiple vaccinations given to personnel in the UK armed forces in preparation for deployment to Iraq are not associated with adverse health consequences when vaccinations are recorded objectively from medical records. Adverse health consequences associated with self reported multiple vaccinations could be explained by recall bias.


  • We thank the UK Ministry of Defence for their cooperation; in particular we thank the Defence Medical Services Department, the Defence Analytical Services Agency, the Armed Forces Personnel Administration Agency, and the Veteran’s Policy Unit.

  • Contributors: DM was the lead author in writing the paper and participated in the conduct of the research and analysis. MH was principal investigator, sought funding, and participated in planning, supervision of data collection, writing of the paper, and commented on the analysis and writing. SW was principal investigator, sought funding, led the planning of the study and supervision of data collection, and commented on the analysis and writing of this paper. DM, MH, and SW are guarantors.

  • Funding: UK Ministry of Defence. The work was independent of the funders but a copy of the paper was sent to them. The Defence Analytical Services Agency provided the sampling frames of the armed forces. The funders did not participate in data collection, data processing, data analysis, or interpretation of findings. MH and SW are funded by NIHR Biomedical Research Centre for Mental Health, South London and Maudsley NHS Foundation Trust, and Institute of Psychiatry, King’s College London.

  • Competing interests: SW is honorary civilian consultant adviser to the British army.

  • Ethical approval: Ministry of Defence (Navy) personnel research ethics committee and the King’s College Hospital local research ethics committee.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

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