Considering recombinant herpes zoster vaccine for fragile pediatric patients: A new opportunity

Background: A recombinant vaccine is approved to prevent herpes zoster (HZ) in adults ≥50 years and immunocompromised individuals ≥19 years. However, in children, the live attenuated vaccine remains the only prevention strategy against varicella zoster virus (VZV), with only one trial evaluating the safety and immunogenicity of GlaxoSmithKline's HZ subunit candidate vaccine in immunocompromised children. Objectives: To estimate VZV burden in our third level pediatric hospital and identify high-risk pediatric groups for its occurrence and complications to explore the need for an inactivated vaccine. Methods: We reviewed VZV/HZ hospital discharge codes and positive VZV molecular tests at Meyer Children's Hospital from January 2018 to May 2023. We categorized patients based on their vaccination status as unvaccinated, partially vaccinated (single dose), or fully vaccinated (complete two-dose regimen). 96 controls from the same Departments and period were also included to assess VZV vaccine effectiveness. Results: Of 48 patients with VZV (52 % female; median age: 11.6 years [IQR: 7–14.2]), 10 had chickenpox and 38 HZ; 2/48 (4.2 %) received 2 doses of vaccination, 10/48 (20.8 %) were immunized with 1 dose and 36/48 (75 %) were unvaccinated. Immune-related comorbidities were present in 20/48 (42 %) patients, and among those with HZ requiring hospitalization, comorbidities strongly predicted admission (OR 4.71; 95 % CI, 1.23–20.39; p = 0.028). Full vaccination was more frequent in controls (43/96, 45 %) than in cases (2/48, 4.2 %; p < 0.001). Conclusions: In our cohort, many cases had comorbidities contraindicating the live attenuated vaccine. If proven safe and effective, the recombinant HZ vaccine could offer a preventive option for immunocompromised children ineligible for live viral vaccines.