The MMR vaccine is a superhero, protecting children from four nasty diseases: measles, mumps, rubella, and varicella (chickenpox). To make sure this protection is extra strong, it’s actually given in two doses.
The first dose is typically given to babies between 9 and 15 months old. Then, to ensure long-lasting immunity, a second dose is given when they are between 15 months and 6 years old. There needs to be at least a 4-week wait between the two doses for them to work best.