The epidemiology of varicella cases among children in Beijing's Fengtai District from 2008 to 2012.

In recent years, the number of breakthrough cases of varicella (onset >42 days after vaccination) increased each year, and varicella outbreaks continue to occur in Beijing. Data from the Immunization Information System and the Infectious Disease Reporting System demonstrated that in Beijing's Fengtai District, the varicella breakthrough rate increased from 0.7% in 2008 to 2.5% in 2012 and showed an increased trend (P<0.001). Among the varicella cases in children (age of 3-15 years), the number of breakthrough cases increased from 167 in 2008 to 622 in 2012, which was 45.2% (n=1735) of the total child cases (n=3842). From 2008 to 2012, a total of 62 outbreaks occurred; among the 787 affected child outbreak cases, 61% were vaccinated. Altogether, the results from this study indicated that 1-dose vaccination cannot sufficiently prevent the occurrence of breakthrough cases of varicella or control varicella outbreaks in Beijing's Fengtai District.