Background: To find out the presence of hepatitis A antibodies (anti-HA) in an urban population of Madrid, age ranging from 6 to 18 years. At the same time, the immunity level is evaluated with respect to measles, rubella and mumps in a sub-group aged between 6 and 13 years old.
Methods: The study was carried out in two schools population of the north area of Madrid.
Results: Anti-HA prevalence in the whole population under study (707 subjects) was of 6%; a direct correlation was observed between prevalence and age. With respect to the seroprotection study against measles, rubella and mumps, 81% out of the 385 vaccinated subjects is protected against the three viruses. Seroprotection rate is of 79% if this is evaluated with respect to the total 6-13 age group under study (458 subjects).
Conclusions: The results of anti-HA prevalence obtained in the eldest groups reveal that a high percentage of the study population aged 17 (92%) and 18 (84%), is anti-HA negative, which means that they might be susceptible to the infection when reaching the adult age. 21% of the school age group studied with respect to measles, rubella and mumps is seronegative to some of the three viruses. Considering the above results, it appears that it could be interesting to evaluate whether the administration of a booster dose to children in school age would enable to reduce the number of unprotected subjects in the referred ages.