RESPONSES OF CHILDREN TO BOOSTER IMMUNIZATION WITH THEIR PRIMARY CONJUGATE HAEMOPHILUS-INFLUENZAE TYPE-B VACCINE OR WITH POLYRIBOSYLRIBITOL PHOSPHATE CONJUGATED WITH DIPHTHERIA TOXOID

Children primed with one of four conjugate Haemophilus influenzae type b vaccines received booster immunization with their primary vaccine or with polyribosylribitol phosphate conjugated with diphtheria toxoid. The latter vaccine produced postbooster antibody levels that equaled or exceeded those produced by boosting with the original vaccine, and thus may be used as a booster irrespective of the original vaccine.