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

Background: A combination measles, mumps, rubella, and varicella vaccine (ProQuad®, Merck & Co., Inc, West Point, PA) was evaluated in five clinical trials. Use of ProQuad® 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 dur-ing the clinical development program for ProQuad®. 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® in five controlled clinical trials. M-M-R®II and VARIVAX® 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® in 12- to 23-month-old children was shown to be as immunogenic as a single dose of M-M-R®II and VARIVAX® and was generally well tolerated. ProQuad® 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® compared to M-M-R®II and VARIVAX®, but fever episodes were transient without long-term sequelae. Both a 2-dose regimen of ProQuad® in 12- to 23-month-olds and use of ProQuad® in place of M-M-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® was lower than that following the initial dose. Conclusions: A single dose of ProQuad® is as immunogenic as M-M-R®II and VARIVAX® and is well tolerated in a 1- or 2-dose schedule. ProQuad® should easily fit into the routine immunization schedule.