Search

Immunizing children against Haemophilus influenzae Type b with a two-dose regimen of two different types of vaccine may be as effective as the currently recommended three-dose regimen with a single type. Researchers randomly assigned 321 infants to various regimens of Haemophilus b immunization. Infants receiving the two-dose mixed regimen had higher antibody titers between two and seven months. Although infants receiving the mixed two-dose regimen had lower average antibody titers at seven months, similar percentages of children had antibody titers in the range considered protective against disease., Objective. To evaluate two- or three-dose "mixed" regimens of Haemophilus influenzae type b conjugate vaccines in the priming series. Design. Two randomized clinical trials with 140 and 181 infants, respectively. Setting. Private practices in New Orleans and Chicago. Methods. In trial I, infants received one of four regimens. Two were recommended regimens for polyribosylribitol phosphate (PRP)--meningococcal protein conjugate (M) and PRP--tetanus toxoid conjugate (T). Two mixed regimens consisted of M at 2 months followed by two doses of T or PRP--diphtheria toxoid conjugate (D) at 4 and 6 months. Trial II consisted of three groups. Two were recommended regimens for M and T. The third was a two-dose mixed regimen consisting of M at 2 months and T at 4 months. Parents were interviewed and instructed to record side effects after each vaccination. Serum was assayed for H influenzae type b anticapsular antibody (anti-PRP). Results. Minor differences in safety profiles likely reflected [alpha] error. In trial I, M (lot 0884T, one of several known to have had decreased immunogenicity), probably primed for substantial increase in serum antibody when D or T was given at 4 and 6 months. In trial II, infants who received the two-dose mixed regimen (M from immunogenic lot 0116W at 2 months and T at 4 months) had a significantly higher mean area under the curve than recipients of the three-dose TTT regimen when antibody concentration was plotted against age, although the geometric mean anti-PRP antibody concentration for the MT-recipients was significantly lower at 7 months. Conclusions. M used in trial I may have primed infants despite poor immunogenicity. The two-dose mixed regimen (MT-) in trial II produced a mean anti-PRP antibody concentration with higher sustained anti-PRP concentrations from 2 to 7 months, as judged by the area under the curve, but a lower mean anti-PRP antibody concentration at 7 months. Pediatrics 1996;98:898-904; Haemophilus influenzae type b vaccines, conjugate vaccines., ABBREVIATIONS. PRP, polyribosylribitol phosphate; M, PRP--meningococcal protein conjugate; T, PRP--tetanus toxoid conjugate; AUC, area under the curve; D, PRP--diphtheria toxoid conjugate; HbOC, oligosaccharide [CRM.sub.197] H influenzae conjugate vaccine; DTP, diphtheria [...]

A new vaccine for Haemophilus influenzae type b does not appear to increase adverse effects when injected with diphtheria-tetanus-pertussis vaccine (DTP), but it has advantages and drawbacks compared with a different H influenzae type b vaccine (HbOC). A group of 141 healthy infants attending a private New Orleans pediatric practice were assigned to receive DTP combined with the new vaccine, DTP and the new vaccine as a separate injection, or separate injections of DTP and HbOC at two months, four months, and six months. Blood samples drawn before each immunization and at seven months were analyzed for antibodies. Parents recorded side effects. Infants receiving the combined injection were more likely to experience swelling and redness at the injection site. They had higher antibody titers against H influenzae. However, children receiving HbOC had higher antibody titers to diphtheria and tetanus compared with children receiving the new vaccine. The import of this for disease protection is unknown., ABSTRACT. Objective. To evaluate whether combining Haemophilus influenzae type b capsular polysaccharide covalently linked to tetanus toxoid (PRP-T) and diphtheria-tetanus-pertussis (DTP) in one syringe produced a vaccine that was safe [...]