Pediatric vaccine-strain herpes zoster: a case series

Background/objectives: Herpes zoster (HZ) is caused by reactivation of the varicella zoster virus (VZV), and typically causes a painful, vesicular, dermatomal rash in adults over the age of fifty. However, HZ has been known to present in immunocompetent pediatric patients, which account for under 1% of total cases. Pediatric cases are typically caused by natural infection with VZV, but among vaccinated children up to half of cases can be due to vaccine-strain VZV. We present two such cases of vaccine-strain HZ in pediatric patients.
Methods: This is a retrospective study of two cases seen at UCLA-affiliated sites. PCR and Sanger sequencing, using previously described PCR primers, determined the presence of two vaccine-strain-specific single nucleotide polymorphisms.
Results: We report two cases of vaccine-strain HZ in immunocompetent pediatric patients who had previously received the varicella vaccine, affecting the right thigh in the first patient and the left leg in the second. Varicella-strain VZV positivity was confirmed by PCR. Both patients had received the varicella vaccine at 12 months of age. Both patients achieved complete resolution of symptoms after 7-day courses of acyclovir.
Conclusions: While vaccination against VZV has overall reduced the incidence of both varicella and HZ in US children, given the widespread use of the VZV vaccine, awareness of the possibility of vaccine-induced HZ remains an important consideration.