Recent changes to California State education law (Education Code section 4800) permits schools to enroll students in Transitional Kindergarten at a younger age than previously allowed. Students entering Transitional Kindergarten must have the same immunizations that are required for Kindergarten entry. The Kindergarten boosters can be given as soon as the student turns 4 years old.
The California Department of Public Health has revised its Transitional Kindergarten FAQ's to address questions regarding immunization requirements and younger TK students:
Should students who are 4 years old receive their Kindergarten booster vaccines?