Clinical effectiveness of influenza vaccination in Manitoba

• Published in: JAMA : the journal of the American Medical Association Vol. 270; no. 16; p. 1956
• Main Authors: Fedson, D S, Wajda, A, Nicol, J P, Hammond, G W, Kaiser, D L, Roos, L L
• Format: Journal Article
• Language: English
• Published: United States 27.10.1993
• Subjects: 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; Manitoba
• ISSN: 0098-7484; 1538-3598
• DOI: 10.1001/jama.1993.03510160074032

To assess the clinical effectiveness of influenza vaccination in preventing influenza-associated hospitalization and death. Case-control study. Noninstitutionalized persons aged 45 years or older living in Manitoba, on December 1, 1982, and December 1, 1985. 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. 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. Influenza vaccination has substantial clinical effectiveness in preventing hospital admission and death from influenza-associated conditions in noninstitutionalized individuals.