Clinical signs associated with Triple Antigen (DTP) vaccination in infants

The perceived reactogenicity of pertussis-containing vaccines is of considerable public health importance. The purpose of this study was to establish prospectively the incidence of systemic and local clinical signs associated with the first three doses of the diphtheria-tetanus-pertussis vaccine (DTP) currently used in Australia. In addition, in order to determine whether variability in reporting of such phenomena might be associated with variation in DTP batches, infant behaviour was studied with three batches for the first of the three DTP vaccinations.

Double blind, randomized controlled trial. There were 591 eligible infants who were recruited sequentially from centres for vaccination in three large Melbourne municipalities, of whom 531 (mean age 10 weeks, 45% female) were randomized and immunized. Of 181 subjects who received DTP from batch 1, 151 were studied at the time of their second DTP dose, and 98 at the third. Infants were assigned randomly to receive one of three batches of DTP vaccine. Parents were provided with a thermometer and a clinical sign diary. Research nurses visited the home 24 h after vaccination, and telephoned 7 days after vaccination to record local and systemic signs.

There was no significant variation between DTP batches in rates of local or systemic signs. At the time of the first vaccination, the rates of local signs were: redness 16%, induration 29%, swelling 46%, and tenderness 54%. Systemic signs included: irritability 93%, intermittent inconsolable crying 43%, and persistent crying 12%. An axillary temperature of greater than 38 degrees C was recorded in 13% (CI 9-19%) of babies following the first immunization, 20% (CI 14-27%) following the second, and 14% (CI 8-23%) following the third immunization. There were significant reductions in the rates of observed signs over the immunization course for diarrhoea, irritability, intermittent inconsolable crying and persistent crying.

There is little difference in the rates of clinical signs or presumed minor adverse effects associated with the DTP vaccine used in Australia today compared to that used 10 years ago, despite increases in the diphtheria and tetanus toxoid concentration, and the addition of aluminium phosphate adjuvant. Rates are comparable to those for other DTP vaccines manufactured in North America and Europe.