IMMUNOGENICITY AND SAFETY OF A PERTUSSIS-VACCINE COMPOSED OF PERTUSSIS TOXIN INACTIVATED BY HYDROGEN-PEROXIDE, IN 18-MONTH-OLD TO 23-MONTH-OLD CHILDREN

A new pertussis vaccine, composed of purified pertussis toxin inactivated by hydrogen peroxide and adsorbed onto aluminum hydroxide (NICHD-Ptxd), was injected into 60 children aged 18 to 23 months without a history of pertussis or pertussls vaccination. Two doses of toxoid, 10 and 50 μg, were used. Two injections, given 8 to 12 weeks apart,ellcited increases in serum levels of antitoxin and IgG antibodies in 56 children who had no detectable antitoxin (<5 units) before vaccination. Four children with detectable antitoxin (>-5 units) before the first vaccination had pronounced antibody increases after the first dose. After the second dose, the geometric mean antitoxin concentration was 29 units with the 50 μg dosage and 10 units with the 10 μg dosage (p<0.001). Serum antibody levels elicited by two injections of 50 μg were similar to those in patients convalescing from pertussis. A third injection given to seven children 9 to 10 months after the second injection gave a booster response, with high levels of antitoxin (160 to 1280 units) and of IgG antibodies. With few exceptions the antibody response was restricted to the IgG class. Transient local reactions ≥2 cm in diameter occurred in 14% of the children after the first dose and in 44% after the second and third doses. Moderate fever was recorded after 6% of all injections. There were no changes in peripheral blood leukocyte counts or fasting blood glucose levels measured before and 24 hours after the first injection. We conclude that NICHD-Ptxd is immunogenic in children. No serious adverse effects were noted. © 1990 The C.V. Mosby Company.