A randomised controlled trial with a diphtheria-tetanus-acellular pertussis (dTpa) vaccine in adults

The aim of this assessor-blinded trial was to compare the immunogenicity an d reactogenicity of a candidate diphtheria, tetanus toxoids and acellular p ertussis vaccine with reduced antigen content for diphtheria and pertussis (dTpa) with a licensed reduced adult-type diphtheria-tetanus vaccine Td (re duced diphtheria content) and with an experimental candidate monovalent ace llular pertussis vaccine with reduced antigen content (pa). The dTpa and pa vaccines had identical pertussis antigen content. A total of 299 healthy a dults (greater than or equal to 18 years, mean age: 30.1 years +/- 10.7) we re randomised into 3 groups to receive a single dose of one of the study va ccines. In all groups, clinically significant reactions (severe) were infre quent (0-6%) and no serious adverse events were reported during the study. The incidence of local and systemic reactions following the administration of dTpa was comparable to the Td vaccine group. Of the total study group, p rior to vaccination 52.3 and 93.2% of the subjects had antidiphtheria and a nti-tetanus antibody levels greater than or equal to 0.1 IU/ml, respectivel y; and 73.1, 98.2 and 74.5% of the subjects were seropositive for pertussis toxin (PT), filamentous hemagglutinin (FHA) and pertactin (PRN) antibodies , respectively. One month after vaccination, a similar percentage of subjec ts in the dTpa and Td groups had anti-diphtheria (88.4% vs 90.1%) and anti- tetanus (100% vs 98.9%) antibody levels greater than or equal to 0.1 IU/ml. Similar anti-FHA (100%) and anti-PRN (98.9%) vaccine response rates were s een in the dTpa and pa groups, while the anti-PT vaccine response rates wer e 96.8 and 100.0%, respectively. The dTpa vaccine is as well tolerated and immunogenic as the licensed Td vaccine, and additionally, can also boost an tibodies against pertussis. (C) 2000 Elsevier Science Ltd. All rights reser ved.