MMR and Measles
MMR vaccine is very effective at preventing measles. Kids should get MMR at 12 months, and again at 4-6 years. Kids can also get their second dose as early as 4 weeks after their first dose, they don't strictly need to wait until they’re 4. If they are at least 3 months out from their first dose of varicella (chicken pox) vaccine, this dose can be in the form of MMRV (combination MMR and chicken pox vaccine) and count for both second doses. No special permission is required.
In an outbreak, babies can get MMR as young as 6 months, though they'll still need their two on-time doses. This is not as straightforward because the younger they are, the more likely they are to still have some antibodies they received through the placenta, and these antibodies can interfere with response to the vaccine, not just for this dose, but potentially for all future doses. Please continue to monitor cases locally and discuss with your provider whether a dose at 6-11 months makes sense for your baby.
If you are traveling internationally (or to Texas or another domestic outbreak location), they should absolutely receive MMR early (and hepatitis A vaccine).
Links to local exposures: