December 1996
NEW ORLEANS — A pentavalent vaccine containing acellular pertussis is as immunogenic as the same combination containing whole-cell pertussis vaccine, according to a recent study.
The combination vaccine included diphtheria-tetanus-acellular pertussis (DTaP), inactivated polio vaccine (IPV) and Haemophilus influenzae type b (Hib) vaccine. This vaccine was compared with a similar formulation that included whole-cell pertussis (DTP-IPV-Hib). The study was conducted in Israel and was sponsored by SmithKline Beecham Biologicals, which manufactures the DTaP-IPV-Hib vaccine. The DTP-IPV-Hib vaccine was supplied by Pasteur Mérieux.
The acellular pertussis component contained pertussis toxin, filamentous hemagglutinin and pertactin. The Hib component was conjugated to tetanus toxoid.
Two hundred one infants were included in the study; 101 received DTaP-IPV-Hib and 100 received DTP-IPV-Hib. Vaccinations were given at 2 months, 4 months, 6 months and 12 months of age.
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Children receiving the combination with acellular pertussis vaccine experienced fewer local reactions, such as swelling, pain and redness. Systemic reactions followed a similar trend, with fewer occurring among children receiving the acellular pertussis combination.
The responses to the tetanus and diphtheria components were similar for all children, regardless of which type of vaccine they received. Children who received DTaP-IPV-Hib, however, had a higher geometric mean titer (GMT) to pertussis toxin, filamentous hemagglutinin and pertactin than those receiving the vaccine containing whole-cell pertussis. This trend was similar for all three serotypes of poliovirus.
The response to Hib, however, varied. After the second dose, children who received DTP-IPV-Hib had a significantly higher response. This difference persisted after the third dose, but it was not statistically significant.
All of the children had high GMTs to pertussis antigens following the booster dose, but those who received the acellular pertussis-containing vaccine had a higher response.
The researchers concluded that the combination vaccine containing the acellular pertussis component was as immunogenic as the whole-cell formulation, whereas the acellular vaccine produced superior responses for pertussis toxin, filamentous hemagglutinin, pertactin and poliovirus. The immunogenicity for Hib was not significantly different between the two groups.
"These results are encouraging for further developments of combined vaccines containing acellular pertussis," the researchers concluded at the 36th Interscience Conference on Antimicrobial Agents and Chemotherapy.
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