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’s MMRV family of vaccines: M-M-RII, VARIVAX, and ProQuad.

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