Impact of vaccination against varicella on the reduction of the disease incidence in children and adolescents from Florianópolis, Brazil.

OBJECTIVE To evaluate the impact of universal early childhood vaccination against varicella on the reduction of its incidence in a state capital in southern Brazil. METHODS Official epidemiologic surveillance data from the SINAN database for the 1997-2007 period were used to evaluate the impact of varicella vaccination targeting all children < 2 years of age in Florianópolis (the capital city of the state of Santa Catarina), Brazil, since 2002, thus comprising 5 years before and 6 years after the vaccination. Varicella incidence in Florianópolis was compared with the incidence in the rest of the state for four age groups (< 1, 1-4, 5-9, and 10-14 years). RESULTS Among the 135,311 cases of varicella in the state of Santa Catarina during the 1997-2007 period, 70% were children under 10 years of age. The effectiveness of varicella vaccine ranged from 27 to 38% among the age groups but reached statistical significance only for children 1-4 years old. CONCLUSION The vaccine was effective in reducing varicella incidence in Florianópolis for children 1-4 years old.