The incidence of herpes zoster was 78% lower in children who were vaccinated against varicella, compared with unvaccinated children, according to results of a population-based study published in Pediatrics.
The varicella vaccine was introduced in 1995, and CDC has recommended the routine use of this vaccine in children. Children exposed to wild-type varicella zoster may experience reemergence of the virus, causing herpes zoster. Children who receive the live attenuated varicella virus in the vaccine may also get herpes zoster. Therefore, it’s important to understand how the routine use of the varicella vaccine has affected the incidence of herpes zoster in children.
Weinmann and colleagues conducted an observational, population-based study to assess the incidence of herpes zoster among children older than 12 years (2003–2014) based on their varicella vaccination status. Data on approximately 6.4 million children (ages 0–17 y) was obtained from electronic medical records from six integrated health care organizations. The researchers assessed vaccination status, age at herpes zoster diagnosis, immunosuppressed status, sex, and other factors.
One-half of the children were vaccinated against varicella (n = 3,186,732), and one-half were not (n = 3,185,335), with an almost equal distribution of boys and girls. The crude herpes zoster incidence rate was 38 per 100,000 person-years for children who were vaccinated compared with 170 per 100,000 person-years for those who were not vaccinated. This resulted in a 78% lower rate of herpes zoster in vaccinated children. Overall, the researchers observed that the herpes zoster incidence rate declined by 72% over the study period, with its lowest rate occurring in 2014. When assessed by age group, children aged 1 year who were vaccinated had higher rates of herpes zoster compared with the unvaccinated children; however, this was not observed in any of the older subgroups. Also, the incidence of herpes zoster was lower in children who received two doses compared with only one dose.
CDC recommends two doses of the varicella vaccine for children, with the first dose given at ages 12 through 15 months and the second dose given at 4 through 6 years. The results of the current study suggest that routine immunization with the varicella vaccine has decreased the incidence of herpes zoster in children.
In an accompanying commentary, the author noted that the current results are a “remarkable observation” and suggested the vaccine was less likely to reactivate than wild-type varicella. Areas where additional research is needed were also highlighted and included determining the mechanism for protection against zoster, how long the benefits last, and whether extra doses would be even more beneficial. The author concluded, “Efforts to immunize all children against chickenpox must continue to be made to protect our population from wild-type VZV [varicella].”
Inform parents and caregivers that results of a new analysis suggest that administration of the varicella vaccine decreases the risk of herpes zoster in children. Educate them on the CDC vaccine recommendations (i.e., two-dose schedule) and potential vaccine-related adverse events.
Weinmann S, et al. Incidence of herpes zoster among children: 2003–2014. Pediatrics. 2019;[Epub ahead of print].
Gershon AA. Varicella vaccine: what have you done for me lately? Pediatrics. 2019;[Epub ahead of print].