Immunogenicity of Haemophilus b conjugate vaccine (meningococcal protein conjugate) in children with prior invasive Haemophilus influenzae type b disease.

Children younger than 2 years of age with previous invasive Haemophilus influenzae (Hib) type b disease may not develop protective antibodies to antigens of Hib and may be at risk of developing a second episode of Hib disease. Twenty-three children with prior Hib disease were immunized with Haemophilus b conjugate vaccine (meningococcal protein conjugate). Children 12 to 24 months of age were given one dose of vaccine and children younger than 12 months of age were given 2 doses 2 months apart. Antibody to the polysaccharide capsule of Hib (PRP) was measured by radioimmunoassay. Eighteen children had preimmunization serum antibody concentrations less than 0.150 micrograms/ml. All 18 children responded with greater than 0.150 micrograms/ml of antibody after a single dose of vaccine. Only 1 of the 23 children had a preimmunization serum antibody concentration greater than 1.000 micrograms/ml. Seventeen children ultimately responded with greater than 1.000 micrograms/ml of antibody (P less than 0.0001), concentrations of antibody thought to correlate with protection. Haemophilus b conjugate vaccine (meningococcal protein conjugate) is immunogenic in children with invasive Hib disease. Children younger than 2 years of age with invasive Hib disease should be subsequently immunized with a Hib conjugate vaccine.

Antibody response of 18 month old children 1 month and 18 months following Haemophilus influenzae type b vaccine administered singly or with DTP vaccine.

Seventy-six children (aged 17-19 months) received 10 micrograms of Haemophilus influenzae type b polyribosyl-ribitol phosphate (PRP) vaccine, diluted with either phosphate-buffered saline (PBS) or diphtheria-tetanus-pertussis (DTP) vaccine, in a single-blind randomized trial. There were few side effects when PRP was administered alone. Before vaccination 37 of 76 children (49%) had non-protective antibody levels (less than 0.15 micrograms/mL); 26 of these 37 (70%) achieved antibody levels of greater than 0.15 micrograms/mL 1 month after vaccination. Before vaccination 16 of 76 (21%) had antibody levels of greater than 1.0 micrograms/mL; 1 month after vaccination 39 of 76 children (51%) achieved levels of greater than 1.0 micrograms/mL. Of 12 infants who had antibody levels less than 0.15 micrograms/mL 1 month after immunization, 10 had protective levels 18 months later. Administration of PRP mixed with DTP did not affect antibody response to PRP. The potential use and limitations of PRP vaccine are discussed.

Vertical transmission of group B Streptococcus. Relation to intrauterine fetal monitoring.

A prospective study of 70 mother-infant pairs was designed to evaluate vertical transmission of group B Streptococcus (GBS) in relation to the use of intrauterine fetal monitors (IUFMs). Multiple-site cultures obtained from mothers during the intrapartum interval and those obtained from infants on day 1 and at discharge or day 4 were plated on a selective medium. Thirteen (27.1%) of 48 IUFM-exposed women vs seven (31.8%) of 22 non-IUFM-exposed women had GBS at one or more sites. The GBS colonization with maternally concordant serotypes occurred in eight (61.5%) of 13 infants born to GBS-colonized, IUFM-exposed women vs two (28.6%) of seven infants born to GBS-colonized, non-IUFM-exposed women. While this suggests that vertical transmission of GBS is enhanced by IUFM placement, the differences in these infant rates were not statistically significant.