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Will California's new childhood vaccination mandate actually work?

Yesterday, California became the third state in the nation to impose a vaccine mandate on its citizens. The basic idea is that children who want to attend school need to have their shots. The only way to opt out is with a medical exemption signed by a doctor.

The rationale for California's bill was fairly simple: The state had areas with too many people denying vaccines for personal reasons — a major contributing factor to a measles outbreak that started last year in Disneyland and turned into one of the largest in recent US history. By forcing people to get vaccinated, you can boost rates and avoid deadly and costly outbreaks.

Amid applause for California's hard line on vaccine refusers, the skeptics are weighing in and raising good questions about how this new law will work in practice.

If Californians flock to doctors for medical exemptions, rates might not change

The surgeon and medical blogger Orac notes a loophole in California's policy. He went to the text of the bill and found this clause that basically says that any doctor can waive the requirement:

120370. (a) If the parent or guardian files with the governing authority a written statement by a licensed physician to the effect that the physical condition of the child is such, or medical circumstances relating to the child are such, that immunization is not considered safe, indicating the specific nature and probable duration of the medical condition or circumstances, including, but not limited to, family medical history, for which the physician does not recommend immunization, that child shall be exempt from the requirements of Chapter 1 (commencing with Section 120325, but excluding Section 120380) and Sections 120400, 120405, 120410, and 120415 to the extent indicated by the physician’s statement.

This means that some local, vaccine-skeptical pediatricians like Bob Sears could sign off on delaying shots (despite the science and government guidelines) or abstaining altogether (again, in spite of the overwhelming evidence to the contrary) for murky, pseudoscientific reasons.

With this wiggle room, Orac writes, "It’s hard not to suggest that it means that anti-vaccine pediatricians in California, like Dr. Bob Sears and Dr. Jay Gordon, are already putting money down on a new Lamborghini." That's because patients who don't want vaccines might flock to doctors they know will waive them.

Now, you could say this is the case for medical exemptions for everything, not just vaccines — that a doctor can sign off on whatever he or she deems being medically necessary for a patient (and collect fees for seeing the patient).

But there is a policy solution to this particular problem, and it's been enacted in West Virginia, one of the only other states (along with Mississippi) with a strict vaccine mandate. As Orac writes:

In contrast, in West Virginia, it isn’t just the word of the child’s physician that matters; all requests for medical exemptions are reviewed by an Immunization Officer, who determines if they are appropriate "based upon the most recent guidance from the Advisory Committee on Immunization Practices (ACIP), the American Academy of Pediatrics (AAP), and the American Academy of Family Physicians (AAFP) with respect to medical contraindications or precautions for each vaccine.

So West Virginia asks not only for a signed medical exemption from a doctor, but also for a government immunization officer to approve that request and make sure that it's real.

California's the perfect test of whether a vaccine mandate actually changes vaccination rates

An interesting post at Wired by journalist Katie Palmer points out that California is the perfect testing lab to study the consequences of vaccine mandates. And the lessons from California could help inform policy in other states, many of which are considering similar legislation.


Mississippi and West Virginia both require childhood vaccinations. Mississippi has the highest rate in the country, but West Virginia is number 18. If the mandate was the panacea, she notes, both states should theoretically be at the top.

On the other hand, she writes, there appears to be a link between states that allow both religious and philosophical exemptions to vaccines and lower vaccine rates, but that the pattern doesn't necessarily mean that the policy actually changed the rate. (There could be other factors that explain some of the trends: for example, states that already have a stronger anti-vaccine sentiment may be more likely to have more lax policies.)

So we need better evidence, and California presents a unique opportunity. West Virginia and Mississippi enacted their policies decades ago, making it difficult to figure out how their policies are having an impact on current vaccination. She writes:

Now is the time to test that hypothesis. California is at a historical inflection point. If public health researchers and politicians can look carefully at the state of the state’s vaccination rates and disease numbers before and after SB277 is enacted, they’ll get a powerful tool to either support more bans of these exemptions—several of which are on the table in other states right now—or drive the United States toward different, perhaps more effective strategies to reduce vaccine-preventable disease. Let’s see what comes out of the lab.

Measuring these and other outcomes is a very smart idea that could save lives.