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BACKGROUND: Varicella is a highly contagious vaccine-preventable illness. In 1996, the Advisory Committee for Immunization Practices recommended 1 dose of vaccine for children and in 2006, 2 doses; Connecticut required 2 doses for school entry starting in 2011. Connecticut varicella incidence overall and among persons aged 1–14 years declined during 2005–2008. We examined varicella data for 2009–2013 to determine if incidence continued to decline.
METHODS: Using passive surveillance data, incidence trends and changes in proportion of potentially preventable cases (defined as those among persons not up-to-date with vaccinations and without previous varicella infection) were assessed with chi-square tests for trend and proportion, respectively. Associations between percentages of populations living in poverty (≤100% of federal poverty level) and age-adjusted incidence were evaluated at the census-tract level with Poisson regression.
RESULTS: Varicella incidence per 100,000 persons decreased from13.8 in 2009 to 6.0 cases in 2013 (P <.01); age-specific incidence decreased among groups aged 1–4 years (81.5 to 49.1 cases), 5–9 years (80.1 to 23.9 cases), and 10–14 years (44.2 to 14.5 cases) (P <.01). Incidence was relatively stable among groups aged <1 years (48.5 to 32.7 cases), 15–19 years (7.5 to 5.1 cases), 20–29 years (1.8 to 3.1 cases), and ≥30 years (1.1 to 0.6 cases). Proportion of potentially preventable cases decreased from 44% to 35% (P = .04). Age-adjusted varicella incidence decreased with increasing poverty (P = .02); this association did not remain significant after adjusting for race.
CONCLUSIONS: Connecticut varicella incidence continued to decline overall and among children aged 1–14 years. Further studies should investigate associations between race, poverty and varicella incidence.