This French randomized study compared intramuscular (IM) and subcutaneous (SC) delivery of two doses of the measles, mumps, rubella, and varicella (MMRV) combination vaccination delivered one month apart to 405 children aged 12–18 months. For patients who were originally seronegative for measles, mumps, rubella, or varicella, a 2-dose regimen of MMRV delivered IM was found to be as immunogenic as a 2-dose regimen administered SC for all antigens 6 weeks post-vaccination. The antibody response rates for all vaccination antigens were greater than 99 percent in both the IM and SC groups 6 weeks following the second MMRV dose. When compared to the SC group, fewer patients in the IM group reported injection-site AEs. From Day 0 to Day 4 post-dose 2, fewer individuals in the IM group experienced erythema and edema than in the SC group. The majority of injection-site AEs in both groups occurred during the first four days of immunization, and their severity was mostly minor (2.5 cm). After each MMRV dosage, the incidences of fever were comparable across the two groups. 

In conclusion, when administered SC or IM, two doses of the MMRV vaccination were highly immunogenic and well-tolerated.