2476. Impact of the Vaccination Strategy on Varicella Burden Disease in Argentina

Abstract

BackgroundVaricella (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 was 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.MethodsDescriptive 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.ResultsVaccination 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% (IC 95% =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% [IC 95% 51.3–53] P <0.001 and –51.4% [IC 95% 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).ConclusionThree 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.Disclosures All authors: No reported disclosures.

Trends in Varicella Burden of Disease Following Introduction of Routine Childhood Varicella Vaccination in Argentina: A 12-Year Time Series Analysis

“…Other studies have previously evaluated the impact of UVV in Latin America [ 22 , 23 , 25 , 37 ]. The findings of this study are consistent with those reported in a previous ecological study conducted in Argentina from 2008 to 2017.…”

“…The findings of this study are consistent with those reported in a previous ecological study conducted in Argentina from 2008 to 2017. The study showed a declining trend in varicella cases and incidence in Argentina from 2006 with differences becoming more pronounced in 2017, resulting in a 50% reduction in varicella incidence [ 22 ]. Similar reductions in incidence were also observed for Brazil and Uruguay following the introduction of UVV, ranging from 38% to 87% [ 23 , 25 ].…”

“…One dose of single-antigen varicella vaccine has been reported to be 85% effective at preventing any form of varicella [ 19 ], with two doses increasing this to 98%, with 100% protection against severe varicella [ 19 ]. Despite the proven benefits of varicella vaccination, there are currently only 17 countries in Latin America that have implemented one-dose or two-dose UVV programs, [ 20 , 21 ] and few countries have published post-implementation data on the impact of UVV [ 22 , 23 , 24 , 25 , 26 ].…”