Children who did not receive varicella vaccination after its introduction had a 78% higher incidence of herpes zoster, or HZ, infection compared with vaccinated children, according to research published in Pediatrics.
Sheila Weinmann, PhD, an epidemiologist at the Center for Health Research at Kaiser Permanente Northwest, and colleagues wrote that routine immunization against varicella was implemented in the United States in 1996. Studies conducted since then have demonstrated “varying degrees of decline” in HZ incidence.
Weinmann and colleagues analyzed electronic medical records for HZ cases among 6,372,067 children aged 0 to 17 years. All cases were reported between 2003 and 2014.
The crude incidence rate of HZ infection was 74 cases per 100,000 person-years. The researchers wrote that the rate of infection among vaccinated children was 78% less than the rate observed among unvaccinated children — 38 vs. 170 per 100,000 person-years (P < .0001).
During the study period, the overall incidence of HZ decreased 72% (P < .0001). Throughout the study, children who were vaccinated had consistently lower annual rates of HZ compared with children who were unvaccinated.
“With this study, we reinforce the benefit of HZ prevention among children through varicella vaccination,” Weinmann and colleagues wrote. “Future pediatric HZ rates may be lower than those reported here during a maturing two-dose varicella vaccination program.”
Like wild-type varicella zoster virus (VZV) infection, a vaccine-strain virus may establish a latent infection that can eventually reactivate, causing HZ. However, Anne A. Gershon, MD, professor of pediatrics at Columbia University Institute of Human Nutrition, wrote in a related editorial that the study findings by Weinmann and colleagues demonstrate that vaccine-type VZV is less likely to reactivate compared with wild-type VZV.
“Efforts to immunize all children against chickenpox must continue to be made to protect our population from wild-type VZV,” she wrote. “Fortunately, antiviral therapy is also available for individuals who are unvaccinated and develop varicella or zoster, but immunization is, as usual, preferable.” – by Katherine Bortz
Disclosures: Please see the editorial for Gershon’s relevant financial disclosures. Weinmann and colleagues report no relevant financial disclosures.