Epidemiology and infection
-
Comparative Study
Comparison between cohorts vaccinated and unvaccinated against influenza and pneumococcal infection.
This study characterizes possible confounders that might make cohorts vaccinated and unvaccinated against influenza and pneumococcal infection different at baseline, with the hypothesis that the two cohorts are comparable. The similarity between health and demographic data was analysed by a randomized, multivariant study addressed to 10,000 persons aged 65 years and older in Stockholm County and was carried out in the form of a postal inquiry during the period December 2000 to May 2001. The study-population response rate was 78%. ⋯ Unvaccinated persons with myocardial disease had nine times more days in hospital than vaccinated persons with myocardial disease. Vaccination against pneumococcal infection had an additional effect with influenza vaccination in reducing hospitalization for chronic lung diseases; influenza vaccination alone did not have this effect. In conclusion, the influenza and pneumococcal-vaccine recipients were older and had significantly more chronic lung and heart conditions than the unvaccinated cohort.