COMBINED DIPHTHERIA, TETANUS, PERTUSSIS, AND HAEMOPHILUS-INFLUENZAE TYPE-B VACCINES FOR PRIMARY IMMUNIZATION

A total of 146 infants were immunised at ages 2, 3, and 4 months with a combined diphtheria, tetanus, pertussis (DTP) - Haemophilus influenz ae type b (Hib) tetanus toroid conjugate (PRP-T) vaccine (Pasteur Meri eux) to assess the antibody response and adverse events associated wit h immunisation. Adverse events, including fever; were recorded by pare nts in a diary for three days following each injection, Blood was take n before the first immunisation and four weeks after the third immunis ation to assess antibody response. Data were compared with those from historical controls who had received DTP and PRP-T vaccines by separat e injection. The combined vaccine was well tolerated. Rates of local a nd general reactions were similar to those reported for infants immuni sed by separate injection. All infants achieved protective antibody ti tres (> 0.01 IU/ml) for diphtheria and tetanus; 98% acquired Hib (PRP) antibody > 0.15 mu g/ml and 82.5% > 1.0 mu g/ml. Pertussis antibody t itres (pertussis toxin, filamentous haemagglutinin, total agglutinins, and agglutinins 2 and 3) showed appreciable rise following immunisati on. DTP and PRP-T vaccines provide similar antibody responses and adve rse effects whether mixed in the same syringe or administered by separ ate injection. The vaccines could be combined for use in the United Ki ngdom primary immunisation schedule.