Safety and Immunogenicity of 7-Valent Pneumococcal Conjugate Vaccine in Children Receiving Solid Organ Transplants

Overview

We plan to study whether the 7-valent pneumococcal conjugate vaccine (Prevnar™) is safe and effective in protecting children who have had a solid organ transplantation and healthy children from pneumococcal infections. We expect that two or more doses of Prevnar™ will result in similar antibody responses among transplant recipients compared with healthy control subjects, and that children who have undergone solid organ transplant will have a similar number of serious vaccine-related adverse events within 7 days after Prevnar™ as the healthy patients.

Solid organ transplantation (SOT) has emerged as a lifesaving therapy for many patients with end organ failure. SOT recipients have a lifelong increased risk for infections as a result of immunosuppression, including those caused by pneumococci. The increased susceptibility to pneumococcal infections is multi-factorial and is related to underlying immunosuppression as well as varying degrees of splenic dysfunction as a result of underlying pretransplantation diseases, among other factors. The types and severity of invasive pneumococcal disease vary among each transplant population. However, comparative data are lacking. Lung transplant recipients have the highest incidence of bacterial pneumonia among solid organ transplant recipients. Pneumonia secondary to Streptococcus pneumoniae occurs in heart transplant patients at a rate 10 times that found in the general population. It is suggested that besides the intensity of immunosuppression, ongoing immunosuppression is important as a risk factor for invasive pneumococcal disease in transplant recipients. Despite the fact that 23-valent polysaccharide pneumococcal vaccine is one of the vaccines that receives priority among organ transplant recipients, at the Hospital for Sick Children, several cases of pneumococcal disease have been seen. The advent of the 7-valent conjugate vaccine affords the opportunity to possibly reduce the burden of pneumococcal disease in the patient population by virtue that it may be more immunogenic in transplant patients This study will examine the antibody titres achieved among transplant recipients who are immunized with Prevnar™, as well as evaluate the safety and tolerability or Prevnar™ administered as a three-dose regimen to children and adolescents following organ transplantation.