• MMR (Measles, Mumps, and Rubella)
  • Vaccine Recommendations

Why is a second dose of MMR necessary?

Approximately 7% of people do not develop measles immunity after the first dose of vaccine. This occurs for a variety of reasons. The second dose is to provide another chance to develop measles immunity for people who did not respond to the first dose. About 97% of people develop immunity to measles after two doses of measles-containing vaccine.

Last reviewed: June 19, 2023

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