Effect of fever on the serum antibody response of Gambian children to Haemophilus influenzae type b conjugate vaccine

Background. Acute malaria is a major pediatric problem in developing countr ies and it is known to be immunosuppressive. Methods. The serum antibody response to Haemophilus influenzae type b (Hib) conjugate vaccine was investigated in children ages 12 to 30 months with f ever associated with malaria, fever associated with other causes or no feve r. Groups of 57 children with malaria, 57 children with fever without malar ia and 60 healthy children were bled and vaccinated with a single dose of H . influenzae type b capsular polysaccharide-tetanus protein conjugate vacci ne. Of these 137 were bled again 1 to 2 months after vaccination, Results. The median antibody titers at baseline were low and similar in the three groups; 77, 65 and 57% of children in the malaria, febrile and healt hy groups, respectively, had prevaccination titers of anti-polyribosylribit ol phosphate antibodies below 0.15 mu g/ml. The median antibody titers afte r vaccination were 6.3, 7.5 and 23 mu g/ml in the malaria, febrile and heal thy groups, respectively (P < 0.001, healthy group vs, the two febrile grou ps). All the healthy children had protective titers (>0.15 mu g/ml) after v accination, but 11% of the children with malaria and 4% of the other febril e children did not have protective titers. Conclusions. Anti-polyribosylribitol phosphate titers after Hib vaccination were lower in children with malaria or other febrile illnesses at the time of vaccination than in controls. Fever associated with malaria or other ac ute illnesses is associated with a diminished response to Hib conjugate vac cine. These findings raise questions about the vaccination of febrile child ren and indicate the need for further studies in this area.