The key difference is what they protect against: MenACWY guards against four types (A, C, W, Y) of bacteria causing meningitis and septicemia (blood poisoning), while MMR protects against three highly infectious viral diseases: Measles, Mumps, and Rubella.

MenACWY is often recommended for young adults, especially students, to prevent serious bacterial infections, whereas MMR is a routine childhood vaccination given in two doses.