Delayed vaccination, asthma and development disorders linked to slightly higher rates
FRIDAY, Dec. 4 (HealthDay News) -- The incidence of shingles (herpes zoster) resulting from the reactivation of the latent varicella-zoster virus following vaccination for chicken pox is very low, but the risk may be higher for children with asthma or those vaccinated later, according to a study in the December issue of Pediatric Infectious Disease Journal.
Hung Fu Tseng, Ph.D., of Kaiser Permanente in Pasadena, Calif., and colleagues studied medical records of 172,163 children who were vaccinated with a single dose of varicella vaccine from 2002 to 2008 for subsequent diagnosis with herpes zoster as well as chronic conditions they had prior to diagnosis.
In 446,027 person-years of follow-up, the researchers found that the overall herpes zoster incidence rate was of 27.4 per 100,000 person-years. Children who were at least 5 years of age when vaccinated had a slightly higher incidence rate than children vaccinated between 12 and 18 months of age (34.3 versus 28.5 per 100,000 person-years). For children vaccinated between 12 and 18 months, the herpes zoster incidence rate increased each year for the first four years following vaccination, peaking in the fourth year at 43.17 per 100,000 person-years. Among those children who developed herpes zoster, 11.1 percent had asthma, 8.3 percent had developmental disorders, 2.1 percent had psychological disorders, 0.7 percent had lymphoid leukemia, and 0.7 percent abused drugs.
"These data demonstrate that diagnosed herpes zoster is rare among children following varicella vaccine. Despite the small numbers, the roles of delayed vaccination, severe asthma, and development disorders warrant further investigation," the authors write.
The study was supported by a research grant from Merck Research Laboratories, which makes the VARIVAX vaccine.
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