Varicella (VZV) is one of the most frequent exanthematic diseases in childhood. In Argentina, around 150,000-180,000 total cases per year are registered; however, underreport exists and some 400,000 cases are estimated to occur annually. Varicella vaccine (VV) was included in the national immunization schedule (NIS) in 2015, with a 1-dose schedule administered at 15 months of age. The information provided by epidemiological surveillance is essential to evaluate the impact of public health decisions.
Our objective is to describe and to compare the epidemiological situation of VZV infections in Argentina in two periods: pre (2010-2014) and post (2016-2017) vaccine introduction in NIS.
Descriptive study. We compared cases and incidence rates (R) of VZV per 100,000 population (global and disaggregated by age) reported to the National Health Surveillance System; in pre (Pre-VV) and post-vaccination (Post-VV) periods. Data analysis of 2015 was excluded since it was considered a transition year.
Vaccination coverage for 2015 was 44.7%; 74.4% in 2016 and 75.5% in 2017. 728,392 cases of VZV were notified (R = 362,1) in Pre-VV period and 176,995 cases in Post-VV (R = 220,6), with a global incidence rate reduction of 39% (IC95% =38,9-39,6 p <0.001). Both 12-24 months of age and 2-4 years old groups (Pre-VV R 2,253 and Post-VV R 1,077; Pre-VV R 2,400 and Post-VV R 1,165, respectively) showed the greatest reductions in incidence rates (-52.2% [IC95% 51.3-53] p <0.001 and -51.4% [IC95% 51-52] p <0.001). Besides, age groups not affected by vaccination (<1 year, 5-9 years and 10-14 years) presented minor but significant reductions (-49.1% [95% CI 44.5-53.4] p <0.001; -23% [IC95% 22.4-23.6] p <0.001, and -17% [IC95% 16.4-19] p <0.001 respectively).
Three years after the implementation of VZV vaccination strategy, a significant incidence rates reduction is recorded, especially in children <5 years old, despite suboptimal coverage. Improving vaccination coverage will likely reflect a greater impact on the burden of disease.
M. Iglesias, None
N. Katz, None
M. D. V. Juarez, None
M. Pasinovich, None
M. Saralegui, None
C. Biscayart, None