Children vaccinated against chickenpox at much lower risk of developing shingles

Vaccination to prevent chickenpox (varicella) appears to have an added benefit for children—a reduced risk of shingles (herpes zoster). That's the finding of a study in the November issue of The Pediatric Infectious Disease Journal, published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health, a leading provider of information and business intelligence for students, professionals, and institutions in medicine, nursing, allied health, and pharmacy.

Although long-term follow-up is needed, the reduction in shingles among vaccinated children raises the possibility that chickenpox vaccination will lead to a lower risk of shingles in adulthood as well. The lead author is Dr. Rachel Civen of the Los Angeles County Public Health Department.

At Least in Younger Kids, Varicella Vaccine Reduces Later Shingles Risk
The researchers analyzed public health data on chickenpox and shingles among children in Antelope Valley, Calif., between 2000 and 2006. The goal was to determine how vaccination against chickenpox (varicella zoster virus vaccine) has affected the later development of shingles in children. Shingles is a painful, blistering rash that occurs when the chickenpox virus becomes reactivated in the body. Although more common and severe in older adults, shingles can occur in children as well.

The results showed a sharp drop in the rate of shingles in children under age 10: by 55 percent from 2000 to 2006. The reduction in shingles risk was significantly related to chickenpox vaccination: vaccinated children were four to twelve times less likely to develop herpes zoster than unvaccinated children.

What's more, when shingles occurred in vaccinated children, it seemed less severe than in those who were naturally infected with varicella zoster virus. Less than half of vaccinated children had painful shingles, compared to more than three-fourths of those with shingles related to chickenpox disease. The shingles rash also tended to be smaller and confined to a limited area in vaccinated children.

At the same time, there was an unexpected 63 percent increase in the risk of shingles rate older children and adolescents (aged 10 to 19). Although this trend cannot be "confidently explained," the researchers think it's probably not completely the result of chickenpox vaccination. Improved detection of herpes zoster may be a contributor.

Long-Term Reduction in Adult Shingles Risk Possible as Well
Introduced in 1995, the chickenpox vaccine is now recommended for most children; by 2006, the rate of varicella zoster virus vaccination among U.S. children was nearly 90 percent. The vaccine has greatly reduced the rate of chickenpox disease and related complications in children. Like the natural virus, the virus used in the chickenpox vaccine can become reactivated, causing shingles to occur later. It has been unclear how chickenpox vaccination would affect the risk of shingles, in later childhood or in adulthood.

The new results suggest that children vaccinated against chickenpox are at "much lower risk" of developing shingles than those with natural chickenpox disease, Dr. Civen and colleagues conclude. Long-term follow-up studies will be needed. However, if the effect persists over time—together with continued vaccination of future children and reduced exposure to natural varicella zoster vaccine—it may be that the childhood chickenpox vaccination program will lead to a reduced risk of shingles in adulthood as well.