Herpes zoster, also known as shingles, is very
rare among children who have been vaccinated against chicken pox, according to a California-
based Kaiser Permanente study in the December issue of the Pediatric Infectious Diseases Journal.
The study, the largest of its kind, used electronic health records to identify more than
170,000 children vaccinated with the varicella (chicken pox) vaccine from 2002 to 2008 in Kaiser
Permanente's Southern California region, then followed children for an average of two and a half
years to identify the occurrence of herpes zoster.
Researchers found only 122 cases of herpes zoster among the 172, 163 vaccinated children,
for an estimated incidence of 1 case per 3,700 vaccinated children per year. This is a lower rate
compared to what one would expect in the unvaccinated children based on previous
experiences.
"The message to parents and pediatricians is: vaccinating your child against the chicken pox
is also a good way to reduce their chances of getting herpes zoster," said the study's lead
author, HungFu Tseng, a research scientist and epidemiologist at the Kaiser Permanente
Department of Research and Evaluation in Pasadena, California. "More research is needed to
identify the virus strains that cause herpes zoster."
This study did not look at side effects of the varicella vaccine. Herpes zoster is an acute skin viral infection caused by reactivation
of latent varicella-zoster virus, which remains in certain nerve cells of the body after an infection with either wild-type or the varicella vaccine virus. The wild-type virus is found in the natural infection, in contrast to the virus strain found in vaccine.
Since the vaccine's introduction in 1995, there have been few studies on the incidence of
childhood herpes zoster among children vaccinated with the varicella vaccine.
Following licensure in 1995, one-dose varicella vaccine was recommended for children 12
months to 12 years of age. In 2006, a routine second dose of varicella vaccine for previously
vaccinated persons aged 4 years and older was recommended.