How will use of varicella vaccine affect the epidemiology of the disease?
As with all vaccines, use of the varicella vaccine will affect the epidemiology of the disease. Most importantly, the incidence of disease will decline in the population. This has been most notable in two areas conducting active surveillance for varicella as sentinel sites. By 2005, varicella vaccination coverage in these sites had increased to 90% and the reduction in incidence had reached 90% and 91%. The greatest decline in incidence occurred among children ages 1-4 years. However, the decline in incidence has occurred in all age groups, including adults who previously did not have recommendations for varicella vaccine and infants less than 12 months of age who are not eligible for vaccination. This overall decline reflects the protection afforded by the vaccination program at the community level. Use of the vaccine has also affected the clinical characteristics of the illness in that a small percentage of vaccinated persons might develop a modified form of the disease. Varicella di
