The bill, co-authored by California state Senators Richard Pan and Ben Allen, was prompted by the 2014 Disneyland measles outbreak and low levels of vaccination in pockets of California, with some schools having vaccination rates below 60%. SB277 was supported by the California Medical Association, as well as by the American Academy of Pediatrics' California affiliate; the California State PTA; the California Immunization Coalition; and the California Children's Hospital Association. Opposition to the bill, albeit from "a tiny minority", has been characterized as "possibly the most strident outpouring of political dissent in recent memory". Anti-vaccine activists started a petition to have Pan removed by recall election, but failed to obtain the necessary number of voter signatures. Efforts by the Freedom Angels Foundation to place a referendum on the ballot to repeal SB 277 also failed. Opponents of the legislation vilified Pan on social media, comparing to a Nazi; death threats were reported against both him and Ben Allen.
Following the law's enactment, vaccination rates among California schoolchildren increased, although unjustified medical exemptions also increased. A 2019 study published in the journal Pediatrics, analyzing the effect of the law, determined that "the percentage of incoming kindergarteners up-to-date on vaccinations in California increased after the implementation of SB277," but there was a replacement effect: medical exemptions for independent study/homeschooled students largely offset "the decrease in the personal belief exemption rate from 2.37% to 0.56%." The study's correlational analysis also found "that previous geographic patterns of vaccine refusal persisted after the law's implementation." A separate study, published in 2019 in PLOS Medicine used a synthetic control method to "implementation of the California policy that eliminated nonmedical childhood vaccine exemptions was associated with an estimated increase in vaccination coverage and a reduction in nonmedical exemptions at state and county levels," suggesting that the removal of non-medical vaccination exemptions "can be effective at increasing vaccination coverage." The study determined that the "observed increase in medical exemptions was offset by the larger reduction in nonmedical exemptions." The study found that the biggest gains in vaccine coverage were in the counties with the lowest vaccine coverage pre-SB 277.