By: Bialek, Stephanie R. ; Perella, Dana ; Zhang, John
Researchers studied varicella incidence rates and disease characteristics in Antelope Valley, Calif., and West Philadelphia, Pa., and varicella outbreak characteristics in Antelope Valley from 1995 to 2010 to gauge the impact of the introduction of one-dose varicella vaccination in 1995 and the addition of a second dose to vaccination recommendations in 2006. They determined that varicella incidence fell 98 percent in both locations from 1995 to 2010. The incidence fell 76 percent in Antelope Valley and 67 percent in West Philadelphia from 2006 to 2007. By 2010, varicella incidence rates were 0.3 cases per 1,000 in Antelope Valley and 0.1 cases per 1,000 in West Philadelphia. The researchers concluded that the two-dose varicella vaccination program reduced varicella incidence, hospitalization, and outbreaks in the two areas in its first five years, even among infants too young to be immunized.