Evaluation of Trends in Homeschooling Rates After Elimination of Nonmedical Exemptions to Childhood Immunizations in California, 2012-2020.

Introduction: In 2015, California passed Senate Bill No. 277 (SB 277) and became the first state in more than 30 years to eliminate nonmedical exemptions to mandatory childhood immunizations for school entry. One concern that emerged was that the law created an incentive for parents to remove children from brick-and-mortar schools to bypass the immunization requirements. Objective: To assess the trends in homeschooling rates after the elimination of nonmedical exemptions to the requirement of childhood immunizations for school entry. Design, Setting, and Participants: This preintervention-postintervention cross-sectional study calculated homeschooling rates as the number of students in kindergarten through grade 8 (K-8) enrolled through each of California's 3 homeschooling mechanisms (independent study program, private school affidavit, and private school satellite program) divided by all K-8 students enrolled in the same academic year. Data on homeschooling rates were obtained from the California Department of Education. Interrupted time series analyses were conducted using a linear regression model in which the outcome variable was the percentage of students enrolled in a homeschool program before and after SB 277. Data were collected and analyzed from October 3, 2012, to October 2, 2019. Intervention: Passage of SB 277, which eliminated nonmedical exemptions to childhood immunizations for school entry. Main Outcomes and Measures: Homeschooling rates for K-8 students. Results: Among the students included in the analysis, the homeschooling enrollment for K-8 students in California increased from 35 122 students (0.8%) during the 2012-2013 school year to 86 574 students (1.9%) during the 2019-2020 school year; however, the implementation of SB 277 was not associated with an increase in the percentage of students enrolled in homeschooling programs in California beyond the secular trend. The increase in homeschooling was greatest for the lower grade levels: kindergarten homeschooling enrollment increased from 2068 students (0.4%) in the 2012-2013 school year to 10 553 students (1.9%) in the 2019-2020 school year, whereas the grade 8 homeschool enrollment rate increased from 5146 students (1.0%) in the 2012-2013 school year to 10 485 students (2.0%) in the 2019-2020 school year. Independent study programs accounted for 20 149 students (45.3%) of homeschooling enrollment, private school affidavits accounted for 19 333 students (43.5%), and private school satellite programs accounted for 4935 students (11.1%) during the 2015-2016 school year. Conclusions and Relevance: The findings of this study suggest that legislative action to limit nonmedical exemptions for compulsory vaccination for school entry is not associated with removal of students from classroom-based instruction in brick-and-mortar institutions.