From the Journals

Varicella vaccine delivers doubled benefit to children

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As memory of disease fades, vaccine questioning emerges

The finding of a 78% lower incidence of zoster in varicella-vaccinated children is nothing short of “remarkable,” Anne A Gershon, MD, wrote in an accompanying editorial.

But the benefit could be in jeopardy, as parents question the safety and effectiveness of all vaccines, she wrote.

“That the varicella vaccine prevents not only varicella but zoster as well is an exciting dual benefit from the varicella vaccine, further improving the health of children by immunization,” Dr. Gershon said. “Additional studies will be necessary to show the mechanism for the protection against zoster (viral, immunologic, or both), how long this benefit lasts, and whether additional doses of some form of VZV [varicella-zoster virus] vaccine will be more useful.”

But, she suggested, in a time when cases of clinical varicella are dwindling, so is public awareness of the vaccine’s benefit. Clinical varicella is worse for adults than it is for children.

“Efforts to immunize all children against chickenpox must continue to be made to protect our population from wild-type VZV. Fortunately, antiviral therapy is also available for individuals who are unvaccinated and develop varicella or zoster, but immunization is, as usual, preferable,” Dr. Gershon concluded.

Dr. Gershon, a pediatric infectious disease specialist, is a professor of pediatrics at Columbia University, New York. She wrote a commentary to accompany the article by Weinmann et al. (Pediatrics. 2019 Jun 10. doi: 10.1542/peds.2018-3561). Dr. Gershon had no relevant financial disclosures. The commentary was funded by the National Institutes of Health.



Pediatric herpes zoster declined by 72% in the years following introduction of routine varicella vaccination, with the rates in vaccinated children 78% lower than those in unvaccinated children.

Toddler is held by mother while being vaccinated by doctor. KatarzynaBialasiewicz/Thinkstock

The benefit became largely apparent after children received the second vaccination in the recommended series, and persisted throughout childhood, Sheila Weinmann, PhD, of Kaiser Permanente Northern California, Oakland, and colleagues said.*

The analysis included 6.37 million children in the Kaiser Permanente database, 50% of whom were vaccinated for all or some of the study period stretching from 2003 to 2014. Overall, the crude lab-confirmed herpes zoster (HZ) incidence rate was 74/100,000 person-years. When stratified by vaccine status, the crude rate of HZ among vaccinated children was 78% lower than among unvaccinated children (38 vs. 170 cases per 100,000 person years).

Herpes zoster was more common among girls than boys and up to six times more common in immunosuppressed children than in nonimmunosuppressed children.

The authors also found that unvaccinated children benefited from the high rate of vaccination around them. Although the HZ rate was always lower among vaccinated children, the rate among unvaccinated children fell sharply after 2007.

“The trend of decreasing HZ incidence among children who were unvaccinated is likely due to a lack of primary VZV [varicella-zoster virus] infection resulting from herd immunity in a highly vaccinated population,” Dr. Weinmann and her associates said.

There was some variability among age groups, especially among the youngest who were not fully vaccinated.

“In the group aged 1-2 years, the confirmation-adjusted HZ rate among children who were vaccinated was 70% higher than among those who were unvaccinated,” the authors said. In the “older groups, HZ rates were significantly higher in children who were unvaccinated than in those who were vaccinated,” the researchers noted.

The highest incidence was among vaccinated 1-year-olds, who had a 140% higher risk of HZ than did unvaccinated 1-year-olds. But this risk elevation disappeared by age 2 years. For everyone else, aged 2-17 years, the rate of HZ remained significantly lower in vaccinated children.

“Among the small number of children vaccinated at 11 months of age (for whom the vaccine is not recommended), the HZ incidence rate was significantly higher than in children vaccinated at 1 year of age and older. Similarly, children who contract wild-type varicella infection at younger than 1 year of age also have a higher risk of HZ (relative risk, 13.5). The immature adaptive T-cell response in children less than 1 year of age appears less able to contain VZV as a latent infection, compared with older children.

“Our findings for 11-month-olds who were vaccinated should be interpreted with caution because this population included only three cases of HZ and could have included children participating in a prelicensure study with a vaccine formulation different from Varivax,” Dr. Weinmann and her associates said.

Dr. Weinmann and her associates reported no relevant financial disclosures. The study was supported by the Centers for Disease Control and Prevention.

SOURCE: Weinmann S et al. Pediatrics. 2019 Jun 10. doi: 10.1542/peds.2018-2917.

* This article was updated 6/14/2019

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