Background: 1-Dose varicella vaccination was recommended for children in Beijing before November 2012. To further control school-based outbreaks and decrease incidence, a 2-dose vaccination was implemented in 2013. We described the varicella epidemiology and assessed impact of the 2-dose vaccination in Haidian district, Beijing, 2007-2015.
Methods: We examined the estimated incidence and disease characteristics of varicella during 2007-2015 and obtained the 1-dose vaccination coverage for children born during 2005-2013. Number of vaccine doses given was used to indirectly reflect the second-dose vaccination coverage. Overall and age-specific estimated incidences were compared between 2007-2012 and 2013-2015.
Results: A total of 23,497 cases were reported during 2007-2015. Of the 23,497 cases, 13,440 (57.20%) were male, and 68.40% were <20years of age and 70.02% were students and children in kindergarten. The estimated incidence increased from 82 cases per 100,000 population in 2007 to 104 in 2011, before substantially decreasing from 86 in 2012 to 56 in 2015. The median age increased from 14years in 2007 to 18years in 2015. The 1-dose varicella coverage for children at ≥2years of age gradually increased from 74.21% in 2007 to 90.06% in 2015. Compared with 2007-2012, two-fold average vaccine doses were given during 2013-2015, and the overall estimated incidence declined by 34.4%, particularly in children aged 5-9years, with a significantly declined trend in children aged 1-9years and older adolescents aged 15-19years and non-significantly declined trend in adults aged ≥20years, but a significant increasing trend in infants.
Conclusions: The overall incidence of varicella has decreased substantially in Haidian district since 2013, with largest decline in children aged 5-9years. The 2-dose varicella vaccination might not lead to increase in incidence in adults. Long-term surveillance is needed to fully evaluate the long-term impact of the 2-dose varicella vaccination.
Keywords: Chickenpox; Surveillance; Varicella; Varicella vaccination.
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