[Methodology of the 2nd seroprevalence study in Spain].

Seroprevalence studies are designed in population samples to assess the level and distribution of immunity induced by natural infection of certain infectious agents or by immunization against them. The purpose of the 2nd Seroprevalence Study in Spain is to assess the prevalence and distribution of immune status against vaccine-preventable diseases and generated by natural infection by other microorganisms. Pathologies specifically included in the study are: poliomyelitis, diphtheria, tetanus, pertussis, measles, rubella, mumps, varicella, invasive meningococcal disease by serogroup C, hepatitis A, hepatitis B, hepatitis E, hepatitis C and HIV. The study has a similar design of that conducted in 1996, as it is a descriptive cross-sectional study in resident population of 2 to 80 years of age in Spain. Two-stage conglomerate sampling was carried out on the population aged 2 to 80 years living in Spain, with an initial sample size of 10,000 people. The methodology of the study is described in this article.