CATCH-UP PRIMARY VACCINATION WITH ACELLULAR PERTUSSIS VACCINES IN 3-4-YEAR-OLD CHILDREN - REACTOGENICITY AND SEROLOGICAL RESPONSE

In order to evaluate the optimum number of doses for catch-up primary vaccination against pertussis, 248 Swedish children 3-4 years of age w ere randomized to receive either two or three doses of a three-compone nt or a five-component acellular pertussis vaccine. Adverse reactions were mild, but increased with increasing number of doses, especially i n a subgroup of 17 children with serological signs of earlier pertussi s. There were no clinically significant differences between the two va ccines. Antibody levels against pertussis were higher after two doses in this age group than after three doses in infancy. A primary vaccina tion program for older children can use two instead of three doses. (C ) 1998 Elsevier Science Ltd. All rights reserved.