Abstract
Background and Aims: Vaccine-strain herpes zoster (HZ) is a potential adverse outcome of varicella vaccination. Data are needed on the incidence of and risk factors for vaccine-strain HZ among children <18 years of age. The Centers for Disease Control and Prevention (CDC) funded a study at Kaiser Permanente Northwest (KPNW) to determine the number and proportion of pediatric HZ cases caused by varicella vaccine, assess positive predictive value (PPV) of physician diagnosis of HZ, and compute incidence of vaccine and wild-type HZ in the KPNW population.
Methods: We used electronic data to identify all pediatric medical office visits with a HZ diagnosis. During the visit, the provider collected a lesion specimen and completed a questionnaire. The study nurse called to interview the parent and, if no specimen was previously collected, schedule a home visit to obtain it. A follow-up questionnaire on severity and duration of HZ was returned four weeks after rash onset. Specimens were sent to the National Varicella-Zoster Virus (VZV) Laboratory at the CDC for PCR analysis to confirm presence of the virus and classify it as wild-type or vaccine-type.
Results: From 5/2005 to 3/2009, we enrolled 308 subjects in the study. Two-hundred eighty-one (96%) had adequate lesion specimens for PCR analysis. We found VZV in 75% of adequate specimens; 69% were wild-type, while 9% were vaccine-type and 1% (2) were vaccine:wild-type recombination. Among vaccinated subjects, 69% had wild-type HZ. The PPV for provider diagnosis of ‘definite HZ’ was 83%: 85% for unvaccinated subjects and 76% for vaccinated subjects. Incidence rates for vaccine-strain and wild-type VZV in plan children age 0–17 will be presented.
Conclusions: Vaccine-strain VZV was found in a minority of HZ cases in this age group. We observed recombination of vaccine-strain and wild-type viruses in two subjects. Provider diagnosis of HZ was good overall.
- Received May 27, 2010.
- Accepted May 27, 2010.
