Double-blind, randomized study of the effects of influenza vaccination on the specific antibody response and clinical course of patients with Chronic Fatigue Syndrome – Source: Canadian Journal of Infectious Diseases, Sep/Oct 2000

Objective: To determine whether influenza immunization is associated with early side effects, a deleterious impact on the illness course and depressed antibody response in patients with chronic fatigue syndrome (CFS).

Design: Prospective, randomized, double-blind, placebo controlled trial. CFS patients and healthy volunteers filled out a questionnaire on immunization side effects and had hemagglutination-inhibiting (HI) antibody titres measured pre- and three weeks after immunization. CFS patients completed symptom and function questionnaires before and during the six-week, postimmunization period.

Setting: Ambulatory care.

Population Studied: Convenience sample of 40 CFS patients fulfilling the Centers for Disease Control and Prevention criteria and 21 demographically matched healthy volunteers.

Interventions: CFS patients were randomly selected to receive commercially available whole virus influenza vaccine (n=19) or an injection of saline placebo (n=21). Healthy volunteers received vaccine only.

Main Results:

  • As a group, immunized CFS patients had lower geometric mean HI antibody rises than healthy volunteers (P<0.001).

  • However, there was no difference in the rates of fourfold titre rises, and immunization did achieve a probably protective titre (1:32 or greater) in most CFS patients.

  • No difference could be detected between immunized and placebo CFS patients in immunization side effects, although CFS patients as a group reported four times as many side effects as healthy volunteers.

  • Further, in the six weeks following immunization, placebo and immunized CFS patients did not demonstrate any differences in terms of functioning, symptom severity and sleep disturbance


Conclusions: In patients with CFS, influenza immunization is safe, not associated with any excess early reactions, and stimulates an immunizing response comparable with that of healthy volunteers.

Source: Canadian Journal of Infectious Diseases. 2000 Sep;11(5):267-73. PMID: 18159300, by Sleigh KM, Danforth DG, Hall RT, Fleming JA, Stiver HG. Division of Infectious Disease, Department of Medicine, Vancouver, BC, Canada.

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