Impact of the tetra viral vaccine introduction on varicella morbidity and mortality in the Brazilian macro regions.

Objective: To describe the impact of the introduction of the viral tetra vaccine in the National Immunization Program in 2013 for 15-month-old children in mortality rates and hospitalization associated with varicella in Brazil.

Methods: Mortality rates and hospitalizations rates associated with varicella were evaluated between 2010 and 2016 and described according to Brazilian macro regions and age. The population was stratified into age groups: < 1year, 1-4 years, and 5-14 years. Data were collected from the Informatics Department of the Unified Health System. A percentage difference was calculated between rates of hospitalizations and mortality in the pre (2010-2012) and post-vaccination periods (2014-2016) to estimate the approximate effectiveness of the vaccine.

Data Synthesis: At the national level, vaccination significantly reduced the mortality rates and hospitalizations rates in all age groups analyzed. Among those under 5 years of age, mortality rates and hospitalizations rates decreased 57-49% and 40-47%, respectively. There was a national decrease of up to 57% in the mortality rates due to the disease, with smaller decreases seen in the North and Northeast regions and the largest in the South and Southeast regions. The hospitalizations rates for varicella reached a maximum national decline of 47%. In children aged 1-4 years, with higher vaccination coverage, the highest reduction was observed in both mortality rates and hospitalizations rates, which decreased from 2.6 to 0.4/100,000/year.

Conclusions: The tetra vaccine proved to be effective in reducing both mortality and hospitalizations of children and adolescents up to 15 years of age in the 2014-2016 triennium.