Background: Vaccines are important to prevent life-threatening infectious diseases. This is also, and particularly, true for children with primary and secondary immunodeficiency who have an increased risk of complications and hospitalizations upon exposure to vaccine-preventable diseases. We aimed to measure vaccination coverage and seroprotection in children with primary immunodeficiencies (PID) and solid organ transplantation (SOT) in a university hospital in Flanders, Belgium.
Methods: Serological testing was performed on blood samples of 123 patients aged 2-16 years. Antibody titers were determined by ELISA (MMR) and multiplex assays (DTP) and were considered seropositive if above cut-off value. Vaccination status was assessed retrospectively by parental questionnaire. In particular, vaccination data were copied from relevant documents, verified against the Flemish vaccination register and missing data were requested from the general practitioner. Patients were considered fully vaccinated if they were correctly vaccinated according to the Flemish immunisation programme.
Results: protection against vaccine-preventable diseases measles mumps rubella, diphteria, pertussis but not tetanus, is signficiantly lower in immunocompromised children, compared to historical data found in literature. This is true even in fully vaccinated children and in children on immunoglobulin substitution. Detailes follow at presentation.
Conclusion: Immunocompromised children remain at risk for vaccine preventable diseases. This is due to the nature of their disease and due to the immunosuppressive medication in SOT. Increasing the vaccination status of not only immunocompromised children, but also of healthy children to prevent circulation of vaccine-preventable diseases remains extremely important. The protective under IG substitution should be examined more in depth.