While the risk for developing meningoencephalitis in children who develop herpes zoster after the varicella vaccination is low, observation is still necessary in this patient population. This is according to study results published in the Journal of Child Neurology.
Researchers performed varicella zoster virus (VZV) serology for the assessment of immunoglobulin M and immunoglobulin G antibodies. In addition, the researchers performed VZV sequencing on DNA taken from cells and collected a swab by abrading skin vesicles. Total DNA was extracted, and 2 of the viral genome sections were polymerase chain reaction-amplified, including the first 1500 bases. Furthermore, the investigators aligned generated sequences to the VZV reference sequence and used the EMBOSS program diffseq to generate differences between the consensus sequence and the VZV reference.
In a case of a 20-month-old child who received the varicella vaccine and developed herpes zoster, the vaccine virus was found to be a wild-type variant with a mutation in ORF0. The patient had no neurologic or sensory deficits, but did show allodynia to light touch at the rash site. The rash and symptoms slowly resolved after a 10-day treatment with acyclovir suspension. In a pair of siblings who were vaccinated, a rash developed after 7 months of the vaccine in 1 child, and the other child also appeared to have developed a rash in the same period. A case also developed asthma after herpes zoster; however, autoimmune disease was absent in all cases. Considering the development of herpes zoster in the dermatomes is rare in pediatric patients after wild-type varicella, the researchers believe that the vaccine virus is likely the cause of herpes zoster of the lumbar dermatomes.
A limitation of the study included the analysis of only 3 case studies, which may reduce the generalizability of the findings across the pediatric population.
“Undoubtedly, there are similar cases of herpes zoster without rash following varicella vaccination that are leading to undiagnosed meningoencephalitis caused by vaccine virus in children,” the researchers added. “Therefore, we recommend increased use of the newly available multivalent Biofire Filmarray multiplex [polymerase chain reaction] system to screen cerebrospinal fluids from immunocompetent children with new-onset encephalitis for multiple pathogens.”
Moodley A, Swanson J, Grose C, Bonthius DJ. Severe herpes zoster following varicella vaccination in immunocompetent young children [published online January 10, 2019]. J Child Neurol. doi: 10.1177/0883073818821498