title: Varicella vaccination in pediatric oncology patients without interruption of chemotherapy.
abstract: BACKGROUND
  Morbidity and mortality from primary varicella-zoster virus (VZV) infection is increased in immunocompromised children. Vaccination of VZV-seronegative cancer patients with live-attenuated varicella vaccine is safe when chemotherapy is interrupted. However, VZV vaccination without interruption of chemotherapy would be preferable.
  
  
  OBJECTIVE
  To vaccinate VZV-seronegative pediatric oncology patients with live-attenuated VZV vaccine without interrupting their chemotherapy.
  
  
  METHODS
  We performed a single-center prospective cohort study.
  
  
  RESULTS
  Thirty-one patients with either a hematological malignancy (n=24) or a solid tumor (n=7) were vaccinated early during their course of chemotherapy. VZV IgG seroconversion occurred in 14 of the 31 patients (45%) after one vaccination. Only 20 patients were revaccinated after 3 months. These were patients who did not seroconvert (5 patients) and patients who serocoverted (15 patients) to induce or sustain seropositivity. Of these 20 patients the final seroconversion rate was 70%. Seven out of the 31 patients (23%) developed a mild rash of which 5 were treated with antivirals and recovered completely without interrupting chemotherapy, and 2 recovered untreated. Of these 31 immunized patients 26 were available for cellular testing. After one vaccination 20 of 26 patients (77%) tested positive for VZV-specific CD4(+) T cells, of which 7 patients had remained VZV-seronegative. After the second vaccination 11 of 11 patients showed VZV-specific CD4(+) T cells to sustain positivity, although 4 remained VZV-seronegative.
  
  
  CONCLUSIONS
  This study indicates that live-attenuated VZV vaccine can be safely administered to closely monitored pediatric oncology patients without interruption of chemotherapy and adaptive immunity was induced despite incomplete seroconversion.
authors.affiliation: Department of Pediatric Oncology, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands. Electronic address: m.d.vandewetering@amc.nl.
authors.forename: Marianne D
authors.initials: MD
authors.lastname: van de Wetering
authors.affiliation: Department of Experimental Immunology, Academic Medical Center, Amsterdam, The Netherlands. Electronic address: m.t.vossen@amc.uva.nl.
authors.forename: Mireille T M
authors.initials: MT
authors.lastname: Vossen
authors.affiliation: Department of Experimental Immunology, Academic Medical Center, Amsterdam, The Netherlands. Electronic address: m.h.jansen@amc.nl.
authors.forename: Machiel H
authors.initials: MH
authors.lastname: Jansen
authors.affiliation: Department of Pediatric Oncology, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands. Electronic address: h.n.caron@amc.nl.
authors.forename: Hubert N
authors.initials: HN
authors.lastname: Caron
authors.affiliation: Department of Pediatric Hematology, Immunology and Infectious Diseases, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands. Electronic address: t.w.kuijpers@amc.nl.
authors.forename: Taco W
authors.initials: TW
authors.lastname: Kuijpers
mesh_terms: D056704:Adaptive Immunity; D000293:Adolescent; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D002644:Chickenpox / Q000209:etiology / Q000276:immunology / Q000517:prevention & control*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004358:Drug Therapy; D019337:Hematologic Neoplasms / Q000150:complications / Q000188:drug therapy / Q000276:immunology; D053061:Herpes Zoster Vaccine / Q000008:administration & dosage / Q000276:immunology; D014645:Herpesvirus 3, Human; D006801:Humans; D016867:Immunocompromised Host; D007223:Infant; D009369:Neoplasms / Q000150:complications / Q000188:drug therapy / Q000276:immunology; D011446:Prospective Studies; D000069078:Seroconversion; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology
chemical_list: D053061:Herpes Zoster Vaccine; D014613:Vaccines, Attenuated
keywords: Pediatric oncology patients; Seropositivity; T cell reactivity; Varicella vaccination