By Kristen Mitchell
A new analysis published by researchers at the Milken Institute School of Public Health found that a 2016 California vaccine law that banned nonmedical or personal belief and religious exemptions to the vaccine mandate boosted protective coverage against measles and other serious childhood diseases compared to other states.
Avi Dor, professor of health policy and management and senior author of the study, said the data also revealed a sharp increase in medical exemptions to the vaccine mandate. These exemptions were concentrated in a few California counties and could lead to deadly outbreaks in the future.
Dr. Dor spoke to GW Today about the study, and what policymakers can learn from California’s vaccination mandate.
Q: Your analysis found that California vaccine coverage rates increased for all required vaccines following the passage of the 2016 law. Do you think that means the law has been successful?
A: Yes, overall the law—repeal of philosophical and religious exemptions—has been successful, yet the success has been partial: about two thirds of the decline in exemptions after the repeal of the law was offset by an increase in medical exemptions granted.
This suggests that tighter oversight of medical exemptions is warranted—as parents may switch to those when other exemptions are no longer available.
Also note that while the law was successful in that it increased childhood immunization rates—by 2.5 percent in the case of the measles vaccine—the increase in coverage could have been significantly higher if closer monitoring of medical exemptions had been implemented so that exemptions would be granted only when truly appropriate.
Q: You speculated that some parents who did not want to vaccinate their children after the 2016 law went into effect had their previous personal belief waivers switched to a medical exemption. Why is that significant?
A: This is a significant problem because measles and other childhood diseases are contagious, and measles is potentially a deadly disease. To assure that measles is eradicated and does not return again, a very high proportion of children must be vaccinated— this is called herd immunity.
Moreover, simply looking at statewide exemption rates may be deceiving. Our research had shown that substantial variations occur between counties, so that in some areas medical exemptions are unusually high. These pockets of high medical exemption rates and low vaccination rates are especially vulnerable to the spread of the disease.
Q: Why is the practice of “shopping for doctors” something to take note of?
A: This practice provides a challenge, but also an opportunity for public policy. It suggests that improvements can be made both in terms of providing clearer guidelines to primary care providers as well as tightening educational and certification requirements for parents. Such efforts can help dispel myths that exist about the harms of vaccines and alert parents to the harms that can result when children are not vaccinated.
Q: What can state lawmakers who are interested in passing similar laws learn from California?
A: California showed great policy resilience, quickly enacting a law that became effective months after the outbreak of measles in that state in 2015.
It should be noted that California is one of a few states that also impose educational and certification requirements on parents to qualify for certain exemptions. However, the requirements are somewhat cursory and not necessarily effective at getting the message across. States like New York that are currently in the process of enacting similar non-exemption repeals should also consider more assertive educational requirements to help parents realize the risks to their children as well as their communities from not being immunized.
