One-dose vaccination associated with attenuated disease severity of adolescent and adult varicella cases in Beijing's Fengtai District.

Background In recent years, the number of varicella cases in adults has significantly increased in Beijing. However, the effect of the vaccination on varicella-related characteristics among adults has not been studied.Methods and Results: Using data from the Infectious Disease Reporting System and the Immunization Information System, we compared the epidemiology and disease severity in breakthrough and unvaccinated varicella cases in adolescents and adults (≥ 15 year-old) from 2008 to 2011 in Beijing’s Fengtai district, China. The results showed that the age (P = 0.003),contact history (90% vs. 73%, P = 0.019) and outbreak cases (10% vs. 1%, P < 0.0001) were significantly differently distributed between the two groups and that both the incidence of moderate-to-severe cases (26% vs. 45%, P = 0.035, OR = 0.446) and varicella-associated fever (49% vs. 66%, P = 0.068, OR = 0.534) were either significantly lower or trended to be lower in the breakthrough group than in the unvaccinated group. Additionally,vacci...