Safety and immunogenicity of a combination measles, mumps, rubella and varicella vaccine (ProQuad®)

Background: A combination measles, MUMPS, rubella, and varicella vaccine (ProQuad(R), Merck & Co., Inc, West Point, PA) was evaluated in five clinical trials. Use of ProQuad(R) would result in fewer injections for children and would facilitate universal immunization against all four diseases. Objective: To describe the combined results obtained from the studies conducted during the clinical development program for ProQuad(R). Methods: A total of 5833 healthy children, 12-23 months of age, and 399 healthy children, 4-6 years of age, received 1 or 2 doses of ProQuad(R) in five controlled clinical trials. M-M-R(R)II and VARIVAX(R) were used as the control for most studies. Safety was evaluated for six weeks postvaccination and immunogenicity was assessed six weeks after each dose by a sensitive assay (ELISA or gpELISA). Results: A single dose of ProQuad(R) in 12- to 23-month-old children was shown to be as immunogenic as a single dose of M-M-R(R)II and VARIVAX(R) and was generally well tolerated. ProQuad(R) can be used concomitantly with other vaccines (hepatitis B and Haemophilus influenzae b). A higher rate of fever was reported after 1 dose of ProQuad(R) compared to M-M-R(R)II and VARIVAX(R), but fever episodes were transient without long-term sequelae. Both a 2-dose regimen of ProQuad(R) in 12- to 23-month-olds and use of ProQuad(R) in place of M-M-R(R)II at 4-6 years were shown to be immunogenic and well tolerated. The incidence of adverse experiences following a second dose of ProQuad(R) was lower than that following the initial dose. Conclusions: A single dose of ProQuad(R) is as immunogenic as M-M-R(R)II and VARIVAX(R) and is well tolerated in a 1- or 2-dose schedule. ProQuad(R) should easily fit into the routine immunization schedule.