ANTIBODY-RESPONSES AND REACTIONS TO THE WHOLE-CELL PERTUSSIS COMPONENT OF A COMBINED DIPHTHERIA-TETANUS-PERTUSSIS VACCINE GIVEN AT SCHOOL ENTRY

To measure the clinical effect of adding a whole cell pertussis compon ent to diphtherial tetanus vaccine (DT) given as a pre-school booster, 190 children aged 4-5 years were randomised by a double-blind method to receive either diphtherialtetanuslpertussis (DTP) or DT vaccine in a I:I ratio at selected clinics in England The geometric mean antibody titres to each of the three pertussis antigens were at least sixfold higher in the DTP than the DT vaccine group and equalled or exceeded t hose in infants immediately after primary immunisation with DTP vaccin e, There were no significant differences between DTP and DT vaccinated children in their diphtheria and tetanus antitoxin levels. The freque ncy of large local reactions and systemic symptoms such as crying and a disturbed night was 2-3-fold higher in the DTP vaccinees than in the DT vaccinees. Medication was given to 44% of DTP and 23% of DT vaccin ees (p=0.006). Although the change to whole cell DTP vaccine at school entry, would result in good pertussis antibody titres, the 2-3-fold i ncrease in reactogenicity, that would be caused may be unacceptable at a time when whooping cough is not circulating widely. Evaluation of a cellular DTP vaccines given as a pre-school booster in children vaccin ated under the accelerated schedule is planned.