Varicella Vaccine Protects Four-Fifths of Schoolchildren
Vaccine 80 to 85 percent effective in 2004 Nebraska elementary school outbreak
MONDAY, July 17 (HealthDay News) -- Eighty-one percent of schoolchildren vaccinated against varicella were protected from infection during a 2004 Nebraska outbreak, reinforcing the case for vaccinating children, according to a report in the July 14 issue of the Morbidity and Mortality Weekly Report.
Health investigators traced the outbreak to an unvaccinated kindergartener who attended a Nebraska elementary school two days before the onset of multiple lesions and a skin infection. Only 115 of the school's 283 students had been vaccinated against varicella.
Eventually, 33 elementary school students aged 5 to 13 developed varicella. This included 15 of 115 vaccinated students, for a 13 percent attack rate, and 18 of 27 unvaccinated students, for a 67 percent attack rate. Sixty-seven percent of vaccinated students had milder cases, versus 11 percent of unvaccinated students.
After authorities recognized the outbreak, parents were asked to keep infected children home until lesions formed crusts and became non-infectious.
"This report corroborates the findings of other postlicensure studies, which indicated that the varicella vaccine is 80 percent to 85 percent effective in preventing varicella of any severity and [95 percent or more] effective in preventing severe varicella disease," the authors write.