Vaccinology Update

Varicella zoster vaccine reduced risk for subsequent herpes zoster by 72%

Herpes zoster (HZ) is a result of reactivation of varicella zoster virus (VZV) sometime after chicken pox, the primary infection caused by the virus. Although the incidence of HZ is lower in children than in adults, it is well described, and children with primary VZV before age 1 year are at greatest risk. Children can also develop HZ after vaccination, but the risk for reactivation following vaccination has been challenging to study, requiring many children infected with vaccine-type virus (vaccinated) and wild-type virus (unvaccinated).

In this study, researchers assessed physician-documented HZ incidence and VZV vaccination status during 2003 to 2014 among 6.4 million children enrolled in six healthcare organizations. Results include the following:

• Overall, 50% of children were vaccinated for VZV during the study period; this rate increased over time, reaching 91% in 2014.
• Incidence of HZ was 74 per 100,000 (61 per 100,000 for laboratory-confirmed HZ) and declined by 72% over time.
• HZ incidence was 78% lower in vaccinated children (38 per 100,000) than in unvaccinated children (170 per 100,000).
• Among 1-year-olds, vaccinated children had a higher HZ rate than unvaccinated children, but among children aged 5–17 years, vaccinated children had a significantly lower risk for HZ than unvaccinated children.
• Children vaccinated with two VZV vaccine doses, as is recommended, had 50% lower risk for HZ compared with those who had received just one dose.

COMMENT

This vaccine does double duty: in addition to protecting children from varicella zoster infection, and all the complications that can result, the vaccine significantly reduces the incidence of herpes zoster. Although further evidence supporting the benefits of vaccinating children should not be necessary, these findings provide just that.

(Weinmann S et al. Pediatrics. 2019 Jul;144(1). pii: e20182917. Epub 2019 Jun 10)