Background. The study was done to verify that concomitant administration of a bivalent Haemophilus influenzae type b-hepatitis B vaccine (Comvax), measles-mumps-rubella vaccine (M-M-RII) and varicella vaccine (Varivax) would be well-tolerated and suitably immunogenic with respect to all vaccine antigens.
Methods. We randomized 822 healthy 12- to 15-month-old children (1:1) to receive concomitant injections of Comvax, M-M-RII and Varivax (concomitant group) or Comvax followed 6 weeks later by injections of M-M-RII and Varivax (nonconcomitant group). Blood samples taken before and 6 weeks after vaccination were tested for antibodies to all vaccine antigens.
Results. Vaccinations were generally well-tolerated. Children in the concomitant and nonconcomitant treatment groups were similar with respect to the safety endpoint of primary interest (16.1 and 19.5%, respectively, had a fever ≥103°F rectally at any time within 14 days after either of two clinic visits). Fifteen serious adverse events were reported (eight in the concomitant group and seven in the nonconcomitant group); all resolved. Elements of two serious adverse events (fever, fever and measles-like rash; both in concomitant group children) were considered possibly related to vaccination. One child was withdrawn from the study because of a nonserious adverse event subsequently judged to be unrelated to vaccination. Similar proportions of vaccinees in the concomitant and nonconcomitant groups developed satisfactory antibody responses to the H. influenzae polysaccharide, polyribosylribitol phosphate (97.8 to 98.7%), hepatitis B surface antigen (99.2 to 100%), measles virus (99.4 to 99.6%), mumps virus (98.4 to 99.2%), rubella virus (100%) and varicella virus (93.2 to 94.6%).
Conclusion. Concomitant administration of Comvax, M-M-RII and VARIVAX at the 12- or 15-month clinic visit is one satisfactory way of delivering some of the multiple vaccines indicated during the second year of life.