[Population study of seroprevalence of antibodies against hepatitis A virus in the Community of Madrid, 2008-2009].

Introduction: Seroprevalence surveys enable the level of endemicity of hepatitis A (HAV) to be assessed. The aim of this study was to estimate the seroprevalence (SP) antibody against HAV by age group, and compare it with those obtained in previous surveys.

Methods: Observational cross-sectional study. The target population consists of residents from 2 to 60 years old in the Community of Madrid. Two-stage cluster sampling was performed with stratification of first stage units. After signing the informed consent, a serum sample was extracted from each participant and sociodemographic data were collected by a questionnaire.

Results: SP antibodies to hepatitis A is 46.8% (95% CI 44.6 to 49.0). The SP increases with age. It is higher in the population from more endemic countries and people with less education and lower social class. In relation to the previous survey, SP increased in the population under 30 years old, and a decline after that age is observed. If only the autochthonous population and from countries with very low endemicity is observed, the increase is statistically significant in the 2-5 years age group.

Conclusions: Our region has a very low level of endemicity thus, following the recommendations of WHO, vaccination should be targeted at specific risk groups.