sixty 9- to 15-month-old infants were randomly assigned to receive two doses , 1 month apart , of a haemophilus influenzae type b capsular polysaccharide-diphtheria toxoid conjugate vaccine ( prp-d ) or prp vaccine , each containing 20 micrograms prp .
C0717811
haemophilus influenzae type b
C1524027
prp vaccine