In one of these trials, a randomized, multicenter study, 882 infants were assigned in a 3:1 ratio to receive either PROCOMVAX or Merck Haemophilus b Conjugate Vaccine (Meningococcal Protein Conjugate) (Merck PRP-OMPC Vaccine) plus Merck Hepatitis B (Recombinant) Vaccine at 2, 4, and 12-15 months of age, with the children monitored daily for five days after each injection for local reactions and systemic complaints.