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The Danger of the Anti-Vaccine Movement

by Peter Jaret  

Paul Offit, MD, is director of the Vaccine Education Center at the Children’s Hospital of Philadelphia. He has published more than 160 papers in medical and scientific journals in the areas of rotavirus-specific immune responses and vaccine safety. He spoke with Berkeley Wellness about why the anti-vaccine movement is so dangerous to public health.

How many parents choose not to get their kids vaccinated?

Roughly one to two percent of parents choose not to vaccinate their children at all. Between 10 and 20 percent delay or withhold certain vaccinations. What those numbers tell us is that many children are being put at risk of serious, preventable diseases.

Do unvaccinated children pose a risk to other children?

Of course. The best example is last year’s measles outbreak, which started in southern California and spread to 25 states and parts of Canada. Before that outbreak, there was a report by an investigative reporter named Gary Baum. He went from school to school in southern California and found that some elementary schools had vaccination rates less than 50 percent. He wrote an article predicting that this could become the epicenter of measles outbreak. He published it in what’s not thought to be a classic medical journal, the Hollywood Reporter. And he was absolutely right. When you start seeing a fraying of herd immunity, you begin to see outbreaks, starting with the most contagious diseases. And that’s exactly what we’ve seen: measles, mumps, and whooping cough outbreaks.

What is herd immunity?

Call it community immunity. If you get a high enough population of people immunized, then the virus or bacteria will no longer be able to spread. That number doesn’t have to be 100 percent. We started to eliminate polio in this country once we got to about 70 percent. The percentage needed depends on the contagiousness of the virus or bacteria. When we fall short of that number, then you put children who can’t be immunized at risk. About 500,000 people in the US can’t be vaccinated. They may be on immune-suppressing therapy for chronic diseases, for example, or on chemotherapy for cancer. They depend on others to get vaccinated in order to be protected. California recently passed a law, SB-277, that eliminates all non-medical exemptions, including religious and philosophical exemptions. That law passed in part because a little six-year-old boy with leukemia, who couldn’t be vaccinated, stood up at a meeting and said, “What about me? I depend on the people around me to protect me.”

Why are some parents reluctant to get their children vaccinated?

Partly because they’re no longer scared of these diseases, since we don’t see much of them anymore. And often they get bad information from the Internet that makes them afraid of things they don’t need to fear. In the case of measles, in 1998, a now-repudiated researcher named Andrew Wakefield published a paper linking measles vaccine to autism. There was no biological explanation and virtually no data. The paper should never have been published. But the media jumped all over it. The paper has since been retracted. But the fear it created still convinces people to make dangerous decisions for their children.

A lot of misinformation is based on anecdotal evidence. Why is anecdotal evidence so powerful, even in the face of scientific findings?

Anecdotal evidence is a contradiction in terms. It’s an emotional, personal experience, but it isn’t evidence. My child was fine. My child got vaccinated and now my child is not fine. The vaccine did it. That’s not evidence. Let me give you an example. My wife is a physician in private practice. She was in the office helping the nurse give immunizations. While my wife was filling a syringe with vaccine, getting ready to give the inoculation, a four-month-old child in her mother’s lap had a seizure and went on to have epilepsy. If my wife had given that vaccine 5 minutes earlier, the mother would have been convinced that the vaccine caused the seizure. You could present reams of scientific data showing that that particular vaccine doesn’t increase the risk of seizures, but it’s hard to convince a mother who says, “I saw what I saw.”

It’s reasonable enough to ask if the vaccine was responsible. But that’s an answerable question. You can do studies to find out. You look at large numbers of children who did or didn’t get vaccinated and look at rates of autism. And when we’ve done those studies, there’s no association between vaccination and autism. That’s real scientific evidence.

Are religious beliefs one reason some people don’t get their kids vaccinated?

Unfortunately, yes. In 1991, in Philadelphia, where I live, an outbreak of measles began that was centered around two fundamentalist churches that refused to vaccinate their children. Over the course of three months, there were 1400 cases of measles and nine deaths. The city was in a panic. It was a horrifying time. I wrote the book Bad Faith: When Religious Belief Undermines Modern Medicine, and especially a chapter called “Do Unto Others,” partly to exorcise the demons of that experience. The idea of a religious exemption not to vaccinate your child is the equivalent of a religious exemption to practice child abuse. How is it a religious act to expose your child to harm? It seems to me quite the opposite. Choosing not to get your child vaccinated is not a risk-free decision. Anyone who works in a large urban hospital, as I do, sees children die of vaccine-preventable diseases on a yearly basis. And it’s a terrible thing to see.

What do you say to parents who are afraid that a vaccine will harm their children?

I understand their concern. We have vaccines to prevent 14 childhood diseases.They may require 26 separate inoculations in the first few years of life to prevent diseases that most people have never seen, using biological fluids that most people don’t understand. It’s not surprising that parents are afraid. I respect that. What I don’t respect is when hundreds of millions of dollars are spent for studies that show that those fears are ungrounded, and people ignore the evidence and put their children at risk.

How can we counter the misinformation that’s rife on the Internet?

In the 21st century, we’re of the belief that we can master anything. With the Internet, we think we can learn as much as we need to know by going online. But that’s not the case. Let’s say you’re trying to decide whether to give your child the chickenpox vaccine. You look at people’s opinions on the Internet, and you call that research. In fact, if you want to do research on the chickenpox vaccine, you have to read the roughly 300 papers that have been published on the chickenpox vaccine. For that, you would need some expertise in virology, immunology, statistics, and epidemiology. Few parents have that. Few doctors have that. So we turn to panels of experts who collectively have that expertise, people who carefully evaluate the evidence and make the best recommendations on chickenpox vaccination. That message—trust us, we’re experts—is not one that sells in the 21st century. But in fact, if you want the best medical advice, turn to the experts.

What else should be done to make sure children are protected against preventable diseases?

We should do what California just did, and eliminate all non-medical exemptions. Among states, Mississippi has the highest vaccination rate, over 99 percent. Why? Because they have no non-medical exemptions. In a better world, information wins. You provide people with reliable information, presented in a compelling way, and they make the best choice. But that doesn’t always happen. Then you need to compel people to do what’s right. You don’t give people the option to do something that will hurt their children. You require them to do it. That’s how it works with seatbelts. You can’t get a religious or philosophical exemption and not strap your kid in. We compel people to do it because we know it will save lives. And we know that vaccinations will save many, many lives.

This opinion does not necessarily reflect the views of the UC Berkeley School of Public Health or of the Editorial Board at

Also see Can Non-Vaccinating Parents Be Sued?