NEW YORK (Reuters Health) – A replacement effect may have “stifled” the effect of California’s senate bill 277 (SB277), which banned non-medical vaccine exemptions for kindergarteners, researchers say.
“One unintended consequence of banning personal belief exemptions was the increase in medical exemptions,” Dr. Paul Delamater of the University of North Carolina at Chapel Hill told Reuters Health by email. “New laws will not change parents’ minds about vaccination. Even after SB277 was passed, it appears that parents with personal objections to vaccination were able to avoid vaccinating their children due to the lack of oversight over medical exemptions and the law’s provision that exempted children attending non-classroom-based schools from the state’s school-entry vaccine requirements.”
“The law itself does not address parents’ concerns about vaccines or the misinformation that many are exposed to, which results in vaccine hesitancy and, sometimes, vaccine refusal,” he noted. “Vaccine hesitancy will likely persist until the root causes are addressed.”
In a paper online May 21 in Pediatrics, Delamater and colleagues report on the immunization status of kindergarten children in California before and after passage of SB277.
In the first year after the law was implemented, the percentage of kindergartners entering school who were not up-to-date on vaccinations decreased from 7.15% to 4.42%. Much of the decrease was due to a decrease in the conditional entrance rate, from 4.43% to 1.91% (i.e., in the number of students who entered school having started but not yet completed a full series of required vaccinations).
However, the decrease seen in the personal belief exemption rate – from 2.37% to 0.56% – was largely replaced by other entry mechanisms for students who were not up-to-date, including medical exemptions and exemptions for independent study or homeschooling.
Further, in the second year after the law’s implementation, the percentage of kindergartners not up-to-date increased by 0.45%, despite additional reductions in conditional entrants and personal belief exemptions.
A correlational analysis revealed that previous geographic patterns of vaccine refusal persisted after the law’s implementation.
Like Dr. Delamater, Dr. Adam Ratner, Director of the Division of Pediatric Infectious Disease at Hassenfeld Children’s Hospital at NYU Langone in New York City, expressed concern about the replacement effect and its consequences.
The effect, while worrying, “is not surprising given the widespread promotion of misinformation by anti-vaccine groups through social media and other means of targeting vulnerable parents,” Dr. Ratner, who was not involved in the study, told Reuters Health by email.
“The solution to these issues,” he added, “is elimination of all non-medical exemptions to vaccine requirements, oversight of medical exemptions that are granted to ensure that they are appropriate, and expansion of SB277-like laws to all states.”
“Vaccination of school-age children is essential to controlling disease outbreaks,” he said. “Vaccines are safe and effective, and the ongoing exploitation of vulnerable parents and communities by an unethical, unscientific, and malicious antivaccine lobby needs to be met by a strong legislative public health response. Physicians – especially pediatricians – as well as lawmakers, and parents should accept no less.”