Every state grants vaccine exemptions based on medical need. But since the ’90s, as concern (albeit scientifically unfounded) about a link between vaccines and autism intensified, at least 20 states have allowed opt-outs for “personal belief.” As a result, the percentage of unvaccinated kids has more than doubled nationally. And the number has quadrupled in California, where two out of three kids in some San Francisco schools are unprotected from 19th-century medical terrors.
Now, amid the state’s worst -whooping-cough outbreak in half a century, school officials are cracking down. This fall San Francisco will bar unvaccinated kids from school for three weeks (the disease’s incubation period) after each reported case. But national vaccine advocates want to put an end to check-a-box exemptions entirely, and they may have picked a propitious moment for reform. Most current vaccine mandates grew out of a prior Golden State plague: measles in the ’70s.