Three years ago, California passed a law that did away with personal belief exemptions when it came to not vaccinating children. Because of this parents in the Golden State can no longer choose whether or not their child is vaccinated for any reason other than medical necessity – a loophole that many parents are keen to utilize, according to a study recently published in Pediatrics.

The bill was introduced in 2015 precisely because the personal belief exemption was being used so frequently. During the 2014/2015 school year, only 90.4 percent of kindergarteners attending California's public schools were fully immunized and while it might sound like a lot, it means the state was falling short of its target of 94 percent – the amount medical professionals say is necessary to achieve herd immunity. 

Herd immunity is basically the idea that the entire community (or "herd") of people can be protected against a disease provided a high enough percentage of the said population has been vaccinated against that disease. It means that even those who are unvaccinated are safe because the pathogen cannot spread. It simply does not have enough readily available hosts (ie unvaccinated people) to contaminate.  

The passage of the bill made California the third state (behind Mississippi and West Virginia) to ban all nonmedical exemptions. So, what happened next?

Not-so-shockingly, vaccination rates rose. In the 2017/2018 school year, 95.1 percent of kindergarteners were given the full range of vaccinations – achieving (and exceeding) the herd immunity threshold.

But officials noticed another, more unusual, side effect. The number of medical exemptions (MEs) more than tripled.

There are two things to point out. First, the percentage of parents who sought MEs was still relatively speaking very small, jumping 0.2 percent to 0.7 percent.

Second, there can be really good reasons for not getting your child vaccinated. Children with severe, life-threatening allergies to the vaccine ingredients are advised against it, as are children with a weakened immune system, whether that's due to undergoing medical treatment like radiation and chemotherapy, or a condition like HIV. Some parents who legitimately sought out medical exemptions may have used personal belief exemptions in previous years because they tend to be easier to obtain. This means that at least a small rise was always going to be inevitable.

But to investigate what was going on, researchers conducted a series of telephone interviews between August and September 2017, speaking to 40 health officers and immunization staff from 35 of California's 61 health jurisdictions in total. This is what they found.

Yes, some of the additional medical exemptions were probably legitimate but health officials suspect many were not. Parents have been using reasons (like a family history of allergies or autoimmune disorders) not considered valid by the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices.

What's more, some were actually paying doctors, nurses, and – in at least one case – a medical marijuana dispensary to provide them with exemptions. There are even cases of physicians openly advertising an exemption service for a one-off fee of $150 or more.

So, what should be done about it?

According to Richard Pan, State Senator, and Dorit Rubinstein Reiss, a professor of law at the University of California Hastings College of Law, “Public health officers should have the authority to invalidate unwarranted MEs and revoke the delegation of authority to grant MEs from physicians who abuse it."

"Vaccines are one of the greatest public health successes in history. Mandating vaccination for school is an effective strategy to prevent outbreaks. This protection is undermined when unscrupulous physicians monetize their license and abuse the authority delegated to them from the state by granting unwarranted [medical exemptions]."