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, Ph.D, MPH, a research scientist and epidemiologist at the Kaiser Permanente Department of Research and Evaluation in Pasadena, Calif. "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, 1-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.
Other study authors included: Ning Smith, MS, Lina S. Sy, MPH, S Michael Marcy, MD, and Steven J. Jacobsen, MD, Ph.D., from the Kaiser Permanente Department of Research and Evaluation.
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The above story is reprinted from materials provided by Kaiser Permanente, via EurekAlert!, a service of AAAS.
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