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Vaccination programs form a natural part of the child health services. Owing to other advances in recent decades, increased survival rates in previously lethal pediatric disorders such as cancer, leukemia and end-stage organ failure have been achieved. These diseases can often be cured with chemotherapy and bone marrow or solid organ transplantation. It is estimated that more than 1 million people have been treated with solid organ transplantation since the first kidney transplantation was performed in 1954 [1]. Children with these disorders will be heavily immunosuppressed during treatment and, in the case of solid organ transplantation, for life. As all these children are susceptible to infections, the question of how to handle their immunizations is pertinent. Additionally, immunosuppressive therapy is offered to patients with other immune-mediated diseases. Lastly, in some other diseases, for example chronic liver disease, the vaccination itself may deteriorate the disease, and hence may be dangerous.
There are three major questions that arise when considering vaccination of the immunocompromised child:
*What is the risk of becoming infected with a specific disease that could be prevented with immunization?
*Will the immunologic response offer efficient protection for the child and what is the optimal time for immunization?
*Is there a risk that the immunization itself, be it with living attenuated or component vaccine, can cause damage?
This review article will attempt to provide some answers to these questions, and suggest some limited recommendations. This is important, as it is not uncommon that these children do not receive the full childhood schedule due to fear and uncertainty over what the response to the immunization will be.
Mechanisms of action of active immunization
It is not fully understood how immunity is gained and sustained after vaccination, and to explore this fully is beyond the scope of this review. However, it is clear that many efficient vaccines protect the hosts through the formation of neutralizing antibodies [2,3]; hence, a functional humoral immunity is essential. On the other hand, for live viral vaccines, for example against measles virus, the cellular immunity is important for viral clearance, and children with cellular immune deficiencies develop a severe form of measles infection if infected naturally. In contrast, children with isolated hypogammaglobulinemia (i.e., defect humoral immunity) recover uneventfully from the infection,...