Coverage and predictors of vaccination against 2009 pandemic H1N1 influenza in Madrid, Spain.

This study aimed to ascertain the coverage of vaccination against pandemic influenza in individuals aged over 6 months for whom vaccination is indicated due to a chronic health condition using as data source clinical information recorded in the primary care clinical history. Of all those for whom vaccination was indicated (1,114,632), 14.6% (162,616) finally received the vaccine. There were statistically significance differences in coverage for sex (16.5% for men and 13.1% for women), age groups (5% for people under 30 years and 20% for those over 60), number of chronic conditions (11.1% for one condition, 22.5% for two conditions, and 31.3% for three or more conditions) and depending on the chronic health condition considered. The probability of being vaccinated increased with male sex, age, number of indications, type of medical card (lower among no income) and having been vaccinated against 2009 season influenza. We concluded that the coverage finally reached for those people with an indication due to chronic health condition in the H1N1 campaign was much lower than expected and wished. It is essential to investigate the different factors that could have intervened in the behavior of the population so that more efficient approaches can be adopted in future influenza pandemics.