Preconception Immunization With Haemophilus Influenzae Conjugate Vaccine Adds To Neonatal Immunological Protection

The proportion of neonates with raised Haemophilus influenza type b antibody levels was considerably increased through mothers who received the vaccine prior to pregnancy. These levels also remained high at two months old say American researchers.

A study was undertaken by paediatricians from specialist departments at Institutes and Universities across the United States such as Johns Hopkins, Baltimore, Chicago, Illinois, Baylor College of Medicine, Houston Texas, Dana- Farber Cancer Institute Boston Massachusetts and the National Institute of Health in Bethesda, Maryland, United States. It was designed to determine the potential for pre -pregnancy immunization of healthy women to raise the antibody levels of neonates.

They randomized healthy non- pregnant Pima Indian women of childbearing age to receive one of two Haemophilus influenza type b (Hib). These were conjugate vaccines HbOC or Hib meningococcal outer membrane protein complex (OMP), or a 23-valent pneumococcal polysaccharide vaccine (PnPs).

Infants were given Hib -OMP at two, four and 12 months old. The vaccine safety and immunogenicity was evaluated in the mothers and their babies.

Among the women in both Hib conjugate vaccines groups there were considerably higher anti-polyribose ribitol phosphate antibody titers, by comparison with recipients of the pneumococcal vaccine. They remained high throughout the 37- month observation period.

By comparison with those in the Hib-OMP, the antibody responses to HbOC vaccine were significantly higher. After a subsequent booster dose of each Hib conjugate vaccine, the reactions and antibody responses were similar to those seen following the first dose.

Significantly higher polyribose ribitol phosphate- specific immunoglobulin G (IgG) were noted in infants, both neonatally and at two months old, whose mothers had been immunized with Hib vaccine by comparison with PnPs. However the antibody response to Hib-OMP at six months was lower. And similar titers were seen before and after Hib-OMP boosters at 12 months old.

Concentrations of pneumococcal-specific antibodies were not significantly raised in mothers immunized with PnPs at delivery. In addition, the pneumococcal antibody titers in their infants did not differ from those whose mothers did not receive pneumococcal vaccine preconceptually.