On Mar. 6, 2023, Merck announced that the U.S. Food and Drug Administration had approved the addition of the intramuscular (IM) route of administration to the United States Product Insert for Merckﾒs MMRV family of vaccines: M-M-RﾮII, VARIVAXﾮ, and ProQuadﾮ.

While these vaccines have a long history in the U.S., until now they have only been administered via subcutaneous (SC) injection.