Clinical effectiveness of influenza vaccination in Manitoba

JAMA. 1993 Oct 27;270(16):1956-61.


Objective: To assess the clinical effectiveness of influenza vaccination in preventing influenza-associated hospitalization and death.

Design: Case-control study.

Setting and patients: Noninstitutionalized persons aged 45 years or older living in Manitoba, on December 1, 1982, and December 1, 1985.

Methods: Linked records of the Manitoba population registry, hospital-discharge abstracts, physician claims for ambulatory-patient visits and influenza vaccination, and vital statistics were used. A matched-set analysis estimated the clinical effectiveness of influenza vaccination in preventing hospital admissions and deaths from influenza-associated conditions during influenza A (H3N2) outbreak periods in 1982 to 1983 (12 weeks) and 1985 to 1986 (10 weeks). The analysis adjusted for hospital discharge and ambulatory care for high-risk conditions within the previous 15 months and 3 months, respectively.

Results: Influenza vaccination prevented 32% to 39% of hospital admissions with pneumonia and influenza and 15% to 34% of admissions with all respiratory conditions. Vaccination was 43% to 65% effective in preventing hospital deaths with these conditions (all listed diagnoses) and 27% to 30% effective in preventing deaths from all causes.

Conclusion: Influenza vaccination has substantial clinical effectiveness in preventing hospital admission and death from influenza-associated conditions in noninstitutionalized individuals.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aged
  • Case-Control Studies
  • Disease Outbreaks / prevention & control
  • Disease Outbreaks / statistics & numerical data
  • Female
  • Hospitalization / statistics & numerical data
  • Humans
  • Influenza A virus*
  • Influenza Vaccines* / administration & dosage
  • Influenza, Human / epidemiology
  • Influenza, Human / prevention & control*
  • Male
  • Manitoba / epidemiology
  • Middle Aged
  • Morbidity
  • Risk Factors


  • Influenza Vaccines