The Safety of Oka Varicella in Children Prior to Solid Organ Transplantation

Safety and Immunogenicity of Live Attenuated Oka/Merck Varicella Vaccine in Children Listed to Undergo Solid Organ Transplantation

This study sought to determine the safety of the varicella vaccine pre- and post-transplantation when given to pediatric patients listed for solid organ transplantation. The study assessed the antibody response to a two-dose vaccine regimen and determined the durability of that antibody response at several intervals in the post-transplant period. As a secondary objective, the relationship between antibody titers and different variables were explored

Inclusion Criteria:

• Children > 9 months of age and adolescents < 18 years of age.

• Pediatric transplant candidates who are in any of the following categories:

  1. listed to receive kidney, liver, heart, lung or other or solid organ transplantation in a Canadian transplant centre
  2. not yet officially listed, but are regarded by their physicians as transplant candidates by virtue of their underlying diseases

• No clinical history for varicella.

• Seronegative for antibodies to VZV except infants 9 - 12 months of age who may be seropositive due to maternal antibodies.

• Informed consent obtained

Exclusion Criteria:

• Previous immunization with varicella vaccine.
• Any established immune deficiency (underlying disease or drug induced) or any neoplastic disease
• Children on any oral and / or intravenous steroids within 3 months prior to immunization. Children on inhaled corticosteroids in excess of 800 mcg of beclomethasone dipropionate ( or equivalent ) per day.
• Any exposure to varicella or herpes zoster in the previous 4 weeks involving household, playmate or hospital contacts.
• Inability to delay the transplantation for up to 6 weeks following the last varicella immunization.
• Presence of a person at increased risk for varicella infection in direct and unavoidable proximity with the vaccinees ( e.g. an immunocompromised sibling)
• Past history of varicella or known positive antibody titer for varicella except infants 9 - 12 months of ages who may be seropositive due to maternal antibodies
• Known hypersensitivity to any of the components of the vaccine, including neomycin and gelatin
• Patients whose mothers are known to be seronegative and plan to become pregnant in the subsequent three months
• Administration of VZIG or any other blood products in the previous six weeks (packed red blood cells excepted).
• Any significant infection and/or fever at the time of vaccination
• Any patient receiving or planning to receive salicylates in the six weeks after immunization
• Any patient who has received any live vaccine for 6 weeks or killed vaccine for 2 weeks prior to or after the scheduled VARIVAX™ vaccination.