measles virus virion
This electron micrograph image shows the structure of a single virus particle, or “virion,” of measles virus. Before 1963, about 3 to 4 million people got measles each year and an average of 450 people died, mostly children. After the vaccine became available, the number of measles cases dropped by 98%. (Image: CDC/ Cynthia S. Goldsmith; William Bellini, PhD)

Gov. Jerry Brown has made it just a little bit harder for parents to refuse or skip vaccinations for their children.

By signing AB 2109 into law last month, Brown strengthened one of the nation’s most permissive school immunization requirements. Under existing law, California parents could choose which vaccinations to reject simply by signing a form saying “all or some immunizations are contrary to my beliefs.”

Now, at least, their beliefs will need to be informed by actual science.

State laws require children entering private or public school to get immunized to reduce the risk of spreading infectious diseases to their classmates. All states allow medical exemptions for children with allergies, immunodeficiency or other conditions, and most allow exemptions on religious grounds.

California is one of 20 states that allow parents to opt out of laws requiring children to get vaccinated before they enter school simply because they choose not to.

Costs of easy exemptions
In California, personal belief exemption rates rose slowly between 1996 and 2007, from half a percent to 1.5 percent. But between 2008 and 2010, according to a study published in the American Journal of Public Health in August, the number of children with one or more personal belief exemptions increased by 25%.

That means more than 11,500 kids showed up in classrooms, playgrounds, and after-school activities without their vaccinations in 2010. Even more troubling, the number of kindergartners who attended schools with more than 20 exempted classmates more than doubled. Exempt children are clustering within the same schools, putting themselves—and their peers—at greater risk of an epidemic.

The San Francisco Bay Area has among the highest clustering of exemptions in the state, while Santa Cruz County ranks in the top 10 counties for all three measures analyzed: prevalence (proportion of students with exemptions), exposure (the likelihood a child would interact with an exempt classmate) and vulnerability (a measure of the risk of disease outbreak resulting from compromised herd immunity).

This late 1960s photograph shows a Nigerian mother and her child, who was recovering from measles. The child’s skin is peeling as his measles infection heals. Measles victims in poor countries where other diseases are prevalent often require intensive nursing to avoid complications, including subsequent infections. (Image: CDC)

The resurgence of vaccine-preventable diseases, from pertussis to measles, implicates exemptions in the outbreaks. But without data on the incidence of these vaccine-preventable diseases, says public health researcher Alison Buttenheim, “we can’t say for certain that more personal belief exemptions cause higher disease risk.”

Yet Buttenheim, an assistant professor at the University of Pennsylvania School of Nursing who led the study, says there’s one thing she knows for sure. “Parents who choose not to vaccinate are free-riders, relying on herd immunity maintained by those who do vaccinate to protect their children.”

Though Buttenheim didn’t have the data to study the link, other studies have found that exemptions tend to cluster geographically, increasing the risk of local disease outbreaks.

And in a recent study in the New England Journal of Medicine, states with looser exemption policies also had more cases of pertussis (or “whooping cough”), a bacterial infection that killed 10 infants in California in 2010. (Anyone who thinks babies don’t suffer from pertussis never heard this cough.)

“Vaccine-preventable diseases are going to start in places where people are refusing,” says Roger Baxter, a physician, infectious disease expert and co-director of the Kaiser Permanente Vaccine Study Center in Oakland. “We have lots of evidence of that around the world. We’ve seen it. We know it will happen.”

That’s why some states are requiring parents to think through the risks of leaving their children—and their neighbors’ children—vulnerable to deadly pathogens by refusing some or all pediatric vaccinations.

Last year, Washington (and just last month Vermont) passed laws requiring parents to have a health care professional certify that they received information regarding the risks of immunization, as well as the risks of exposing their family and community to potentially deadly diseases by forgoing immunization.

Under California’s new law, starting January 2014, parents seeking personal belief exemptions must do the same.

The bill, sponsored by state Assemblyman Richard Pan (D-Sacramento), a pediatrician and director of the UC Davis Pediatric Residency Program, is little more than an informed consent law. Anytime you undergo a medical procedure, your doctor is required by law to counsel you on its risks and benefits. The bill requires the same counseling for parents who want to avoid vaccination.

In signing the bill, Brown noted that those “whose religious beliefs preclude vaccinations” don’t need a health care practitioner’s signature. Until the new law takes effect, the state’s philosophical and personal belief exemptions cover religious objections, and parents’ signatures are sufficient in either case.

The myth of 100% safety
But for Baxter, vaccine refusal has veered into religion, with people obsessed with “uber-protection” and vaccine safety. “There’s nothing in this world that’s 100 percent safe,” he says.

“With vaccines, we expect some reactions like fevers or sore arms. But for serious adverse events, where we might expect 1 in 1,000 for most medications, if we see 1 in 100,000 for vaccines, we think it’s too much. Yet many people are worried about things that happen as rarely as 1 in a million. The benefits of vaccines far outweigh that.”

There’s a 1 to 2 in a million risk that the measles-controlling MMR vaccine will cause a serious adverse reaction like encephalitis or pneumonia. By contrast, 1 to 2 of every 1,000 measles cases ends in death.

Just as no vaccine is 100% safe, no vaccine is 100% effective. That’s why the concept of “herd immunity” is so important. When vaccination rates in a community reach a certain threshold (85% to 95% depending on the contagiousness of the disease), then those who can’t get vaccinated—because they’re too young, on immune-suppressing treatments like chemotherapy, or their immune system didn’t respond to the vaccine—are still protected.

But herd immunity relies on high-compliance with recommended pediatric vaccination schedules.

An the trouble is, you’re not likely to know if your child’s vaccination didn’t offer full protection until he comes home sick after going to school, soccer practice, or a play date with unvaccinated peers.

Opportunistic pathogens
In February 2010, the SF Department of Public Health issued a health alert about a measles outbreak. How it started is unclear. But two years earlier, 11 cases of measles in San Diego were traced to a seven-year-old unvaccinated boy who had traveled to Switzerland with his parents and came home with the measles. Within 19 days, he had infected his two siblings, five classmates, and four children—including three infants who were too young to be vaccinated—at his pediatrician’s office. One of the infants had to be hospitalized for severe dehydration, which can be fatal for babies.

The child who started the epidemic went to a school where 36 of 376 children—nearly 1 in 10—had personal belief exemptions.

That’s why some doctors have decided not to see families who shun vaccination. Some regularly treat very sick children and don’t want to risk exposing them to infections that could cause complications and even death. But most doctors that Baxter works with see the informed consent law as an opportunity to explain the risks to parents who didn’t really understand them.

rubella vaccine poster
Typically a mild childhood illness, rubella (also known as “German measles”) can pose a serious threat to the developing fetus if the mother is infected during pregnancy. More than 20,000 babies were born with congenital rubella syndrome (CRS) during an outbreak in 1964-65, before the US vaccine was licensed in 1969. CRS can cause diverse symptoms ranging from deafness to seizures, encephalitis, and developmental delays. (Image: CDC)

Before Brown signed the bill, anti-vaccination activists led by ex-SNL cast member Rob Schneider fought against the bill on the grounds of parental rights, child safety, and a list of myths too numerous to go into here. Incredibly, Sacramento-based TV News Channel 10 gave Schneider 11 minutes to spread his misinformation. He was joined by die-hard anti-vaccination activist Dawn Winkler and Tony Amador, a candidate for the Assembly seat held by the author of AB 2109, Richard Pan.

Activists like Winkler and Schneider tell people that vaccines are dangerous and parents should have the right to decide what’s best for their children. What’s really dangerous, though, is giving people like Schneider — who have little grasp of the facts about vaccines, immunology, or public health — a platform to spread their misinformed beliefs. Infectious disease experts know what Schneider can’t seem to grasp. Infectious pathogens are remarkably adaptable and will readily exploit any weaknesses in herd immunity to make a roaring comeback.

In 2008, a pertussis outbreak at an El Sobrante Waldorf school forced public health officials to close the school temporarily. According to data filed with the California Department of Public Health, 68% of children attending that school have personal belief exemptions on file this year. Only 6% of children there are fully vaccinated.

The San Francisco Waldorf School isn’t far behind, with personal belief exemptions for 59% of children, leaving 22% of students without all their vaccinations. At the Greenwood School in Mill Valley, where 79% of students have personal belief exemptions, only 2% of children are fully vaccinated.

It’s bad enough that people who don’t want to vaccinate are putting they own children at risk, Baxter says. “But they’re also putting their children’s friends at risk, they’re putting little babies who are too young to be vaccinated at risk, they’re putting immune-compromised kids at risk, and they’re putting their classmates at risk.”

People shouldn’t lull themselves into complacency thinking that high vaccination rates in general will protect their kids. “If there’s a pertussis outbreak,” Baxter says, “it’s going to start in schools with high personal exemption rates. Same with measles, varicella, any vaccine-preventable disease. They’re going to start in places where people are refusing.”

Parents have the right to ask school administrators to disclose the exemption rates at their child’s school. You can also go to the California Department of Public Health’s web site to find each school’s exemption rates.

It would be a good thing if parents refused to send their kids to schools with high exemption rates, Baxter says, rather than choosing schools where “parental rights” are viewed as more important than public health.

In the end, he adds, it takes a mandate to bring vaccinations up to the levels that can protect people from these diseases. “It’s the only thing that works because people are busy, or lazy—or have weird ideas.”

Or, in too many cases, they’re getting medical advice from the likes of Rob Schneider instead of a doctor.

Vaccine Waivers, Informed Consent and Public Health 29 October,2012Liza Gross


Liza Gross

Liza Gross, an award-winning independent journalist and senior editor at the biomedical journal PLOS Biology, writes mostly about conservation and public and environmental health. She was a 2013 recipient of the NYU Reporting Award, a 2013 Dennis Hunt Health Journalism fellow and a 2015 USC Data Journalism fellow.

Read her previous contributions to QUEST, a project dedicated to exploring the Science of Sustainability.

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