In the US routine childhood vaccination is required for entry into public school, and in some states even private school. This is a reasonable public health policy. Vaccination not only protects the individual against common infectious diseases, but when enough people get vaccinated this creates community immunity (often referred to as herd immunity) which protects everyone.

Any parent knows first hand that children are seething vectors for germs. Their concept of hygiene, generally speaking, is often not the same as the average adult. Put a large group of children together in a close environment like a school, and you have basically created a disease factory.

Further, some children cannot be vaccinated for medical reasons. They may have a chronic illness that makes their immune systems too weak to handle the vaccine, or they have an intolerance to vaccines. For these children, if they want to attend school, their only protection is the community immunity that results from all the more healthy children being vaccinated. 

Vaccine Exemptions and SB277

Over the decades those with a belief system that lead them to anti-vaccine views have persistently lobbied their state governments to allow for exemptions to mandatory vaccination laws. Much of this lobbying has come from the Christian Scientists, who are often anti-vaccine. They have mostly lobbied for religious exemptions to vaccines, but this has often extended to more permissive non-medical exemptions in general.

America also highly values personal freedom as a general cultural feature. In order to balance the public good and personal freedom the laws do not mandate vaccination for all children – only if you want to enter the school system and mix your child with other children in large groups. If you don’t want your child to be vaccinated, you can home school them.

Whether or not this is the optimal balance of freedom and public good is a matter of debate, but that is where we are. The fight now, when it comes to state vaccination laws, centers around how permissive to make the rules that allow parents to seek exemption from the vaccination requirement to enter school.

All states allow for medical exemptions if children have a medical condition that is a contraindication to vaccination. This is non-controversial. There are three other levels of exemption we can consider: more permissive medical exemptions, religious exemptions, and personal belief exemptions.

Of these religious exemptions are perhaps the most controversial. Even among proponents of science-based medicine, it is unclear if this is a fight we think we can win. We should try, but not necessarily go down with that ship. Eliminating religious exemptions in states that have them is likely to meet the most opposition. Personal belief exemptions (PBE) are the most vulnerable. They are essentially parents saying that they don’t want to vaccinate their kids, and make mandatory vaccine policies an illusion. Definitely we can and should eliminate PBEs in all states.

However, after the Disneyland measles outbreak the political calculus on this issue definitely changed. As we have been predicting on SBM for years, it will likely take a significant return of previously eliminated infectious diseases before the public wakes up about the need for mandatory vaccination. That is exactly what happened. In the wake of the Disney outbreak, California passed SB277, which went into effect on July 1, 2016, and which eliminated all non-medical exemptions, including religious and PBE.

At the same time, however, the bill expanded medical exemptions, giving doctors more leeway in granting it. Previously a medical exemption requires a vaccine contraindication, and now it can include a family history of a reaction to vaccines and other softer indications.

Now it has been a full year since SB277, and JAMA has published an article reporting the results. Overall, the results are good. Non medical exemptions significantly decreased, from 2.37% to 0.56%. However, at the same time medical exemptions increased from 0.17% to 0.51%. Overall vaccine exemptions decreased from 2.54% to 1.06%.

So – bottom line is that SB277 worked. It decreased vaccine exemptions by more than half. These percentages may all seem very low, but it makes a big difference for two main reasons. First, the higher the vaccination rate the more effective is community immunity. Getting a few more percent of kids vaccinated can make a huge difference. Second, these numbers are statewide, and are not evenly distributed. There are pockets of vaccine refusal, and likewise those pockets can be significantly decreased by eliminating PBE.

Of concern, however is the tripling of the rate of medical exemptions. These increased in areas where PBE decreased, and so there does appear to be some substitution. However, it is difficult to interpret exactly what that means. Some parents with children with legitimate reasons for medical exemptions may have used the PBE option because it was easier. A medical exemption requires a letter from a doctor. Now they have to go through that extra step.

But of course some parents who really are just vaccine hesitant may have sought a medical exemption for a questionable reason to replace their PBE. Researchers would have to gather further information in order to resolve this. It also suggests that SB277 can be tightened further, perhaps narrowing the range of what constitutes a legitimate medical exemption, to keep vaccine rates high.

We also know from other studies states with more permissive exemption laws have lower vaccine rates and higher risk of vaccine-preventable diseases. In addition to whether or not they allow religious or personal belief exemptions, states differ on how difficult it is to obtain such exemptions. States that make it harder have higher vaccine compliance.

Overall the data is clear – if we want to optimally protect the public from outbreaks of vaccine-preventable diseases, and to eliminate and perhaps even eventually eradicate some of those diseases, we need to have strong mandatory vaccination laws. Personal belief exemptions all have to go. Religious exemptions should go too, but that will be more of a fight. In those states who allow for religious exemptions, it should be difficult to obtain them (like requiring parental education about the importance of vaccines). Further, medical exemptions should be evidence-based, and not overly permissive.

SB277 was a great step forward, but we can’t stop there. Of the 50 states, 47 of them allow for some combination of religious and personal belief exemptions. There is a lot of work to do.