Interview: Vaccine Expert Dr. Paul Offit

Vaccine expert Dr. Paul Offit is the author of the new book Deadly Choices: How the Anti-Vaccine Movement Threatens Us All. We talked with Dr. Offit about realities of vaccine-preventable diseases, the importance of herd immunity, just how contagious measles really are, why you shouldn’t have chickenpox parties, why neither he nor Jenny McCarthy are autism experts, why it is unethical to run studies featuring vaccinated versus unvaccinated children, and just how extensively the autism-vaccine hypothesis has been debunked.

[update 2/1] Dr. Offit discussed many of these same topics during his 1/31 guest spot on The Colbert Report.

Deadly Choices: How the Anti-Vaccine Movement Threatens Us All

What is your elevator pitch for parents concerned about vaccines and autism?

I think raising the concern is reasonable. Children get vaccines, and for some children, the signs and symptoms of autism may appear soon after receiving the vaccine, so asking those questions is reasonable. The good news is that the question is answerable.

We’ve gone through three different stages, the first being the notion raised by Andrew Wakefield — that the combination measles, mumps rubella [MMR] vaccine caused autism. So now we have studies looking at hundreds of thousands of children who either did or did not get that vaccine, making sure those two groups were alike in other aspects, so you could isolate the effect of that one variable: receiving the vaccine. And that study’s been done, redundantly and repeatedly, and it’s been found that you’re not at greater risk of getting or having autism if you got the vaccine. So MMR didn’t cause autism.

Then we shifted to hypothesis #2, which was “does thimerosal, the ethyl-mercury preservative in vaccines, cause autism?” That was easily studied. Western Europe had taken thimerosal out of vaccines by 1991, the US started taking thimerosal out of vaccines given to young children around 1999. Seven studies looked into this and have all found the same thing, which is that vaccines with thimerosal didn’t cause autism — and also that thimerosal has been out of vaccines given to children less than six months old since early 2000, and the incidence of autism certainly hasn’t declined.

And then we went to hypothesis #3, which is that children are just getting too many vaccines too soon, and that it’s somehow weakening or overwhelming their immune systems. An excellent study by Michael Smith and Charles Woods was published in Pediatrics, and showed that there was no relationship between any developmental delay or autism in children who were fully vaccinated as compared to those who had chosen to significantly delay vaccines.

Everything we know about autism tells you it’s not the vaccines; why are we still focusing on this?

The anti-vaccination camp frequently demands to know why a vaccinated vs. vaccinated study hasn’t been done. The reply is usually that such a study would be unethical — but it sounds like you can draw those comparisons from existing studies — that the study’s effectively already been done.

If you look at the Smith and Woods Pediatrics study, they mined data from Bill Thompson’s thimerosal study at the CDC. Thompson and his colleagues went through the medical records of 1,000 children and carefully documented whether mothers had received RhoGAM that had contained thimerosal prenatally, exactly which vaccines the children were given post-natally, then they subjected the children to 42 different neurological and psychological tests — and concluded that thimerosal wasn’t associated with an adverse neurological outcome.

What Smith and Woods did is take Thompson’s data, and determine which kids got which shots when. They took a group that was fully vaccinated and compared it to a group that was much less vaccinated, who only got two or three vaccines in the first couple years of life. So it wasn’t a vax/unvax, but it was a vaccinated/much less vaccinated study. And there wasn’t any evidence supporting an autism connection.

But you’re right, [a vaccinated/unvaccinated study] is unethical. There’s not an institutional review board in the world that would approve that kind of study, because we know that vaccines work, we know that if you don’t give a large number of children vaccines that some of them are going to get whooping cough or chicken pox, some of them may be hospitalized or even killed by the diseases — you can’t do that kind of study.

People who believe their children’s autism is vaccine-caused seem to mistake coincidence or correlation for causation. Can you give us an example of how that happens?

We’re always looking for reasons why something happened. The example I use is from my wife, who is a pediatrician. She was about to vaccinate a four-month-old baby, and while she was drawing the vaccine from the syringe, the baby had a seizure — and went onto have a permanent seizure disorder. Now, my wife hadn’t given the vaccine yet. But if she had given that vaccine five minutes earlier, there would have been no amount of statistical data in the world that would have convinced that mother that the vaccine hadn’t caused the baby’s seizure. You can do studies that show no increased risk with vaccines and seizure disorders, but that mother might still say “well, that’s true for the population but it’s not true for my child.”

Temporal associations are powerful, and they’re hard to defeat with statistics or studies.

But I would say, and this is going to sound like a contrarian — if my child had autism, I would be motivated to look at the data even more critically, because so much more would be at stake.

In your experience, how representative are the parents like J.B. Handley who refuse to go down the evidence path with regards to their children’s autism?

I’ve actually come around 180 degrees from where I was five years ago. When I wrote Autism’s False Prophets, I thought — wrongly — that most parents believed this vaccine-autism hypothesis. After the book came out, I started getting a lot of letters saying, “I don’t know who you’re talking about — that’s not me. Jenny McCarthy doesn’t represent me.”

A small group of parents represent anti-vaccination ideas. But they’re very passionate, very vocal, very Internet savvy, very media-savvy. And so their voice is much louder than that of the silent majority. My email from parents is 10:1 favorable, thanking me for what I’m doing, etc. I’m encouraged — and in the preface to the paperback edition of Autism’s False Prophets, I apologized to those parents for misrepresenting them.

I think it’s OK to be skeptical, and skeptical about anything you put into your child’s body. But there’s a difference between being skeptical and being cynical. And I think that people like Handley are cynical — he thinks there’s a big conspiracy to sell [vaccine] products and I’m part of that conspiracy. There is no convincing him. And he’s wrong.

If I was the parent of a child with severe autism, I would be really angry with someone like JB Handley for presuming to represent me.

Could you discuss the concept of herd immunity, specifically what it takes to establish it and protect public health?

Herd immunity simply means that you can stop the transmission of a virus or bacteria by having a critical number of the population immunized, and that number really depends on the nature of the virus or bacteria.

For example, Polio was introduced in the United States in 1955. When we got about 70 percent of the population immunized, that effectively eliminated polio, so it couldn’t spread anymore. We eliminated polio from the U.S. by 1979.

Now, measles is much different, much more contagious than polio; you need a higher percentage of the population immunized. Overall the U.S. is in the high 80/low 90 percent immunization rate for measles, but there are certain communities where it’s less than that, about 75 percent, and that’s not good enough. When we had a measles outbreak in 2008, higher than anything we’d seen in a decade, it was in the communities with an erosion in vaccination rates — Southern California, Upstate New York.

You also need to remember, there are about 500,000 people in the United States who can’t be vaccinated, because they’re getting chemotherapy for cancer, or are on immunosuppressant therapy for transplants or other disease. There are also kids younger than six months old who can’t get the flu vaccine or are inadequately immunized against whooping cough because they’re just starting their series. Herd immunity protects them.

Just how contagious is measles?

It’s unbelievably contagious. I’ll give you an example from a study in the New England Journal of Medicine. A 17 year old unvaccinated Indiana girl goes to an orphanage in Romania as part of her church’s mission. She catches measles. She then gets on a plane and comes home. She’s starting to feel ill, fever, runny nose — and she’s starting to get the rash but it’s mild. The next day, she goes to a church picnic with 500 people. She was there for two hours. Of the 500 people there, 465 had either been vaccinated or had developed natural immunity from having measles. Of those 465, 3 of them, 1 percent, got sick. Of the remaining 35 who had never been immunized or had natural immunity, 31 developed measles. 31 out of 35! That’s almost 90 percent! The girl didn’t even have to have direct contact with them — she just had to be in their airspace during a two hour period. That is one contagious disease. And that’s why you need such a high rate of immunization.

People still hold chickenpox parties, and think of chicken pox as a mild childhood disease. But measles can be serious — Roald Dahl’s daughter Olivia died from measles encephalitis, and in your book you listed some rare but fairly gnarly potential measles side effects, including necrotizing fascitis. That’s flesh-eating bacteria, isn’t it?


*Shudder* Can you talk about the risks of vaccine injury versus the risks from contracting vaccine-preventable diseases?

The Vaccine Adverse Events Reporting System (VAERS) is a hypothesis-generating system, a warning system, but it offers no proof. So while it might be a temporal association, that doesn’t mean it’s a causal association.

When the Rotavirus vaccine was introduced in this country in 1998, it appears it could have caused intestinal blockages because there were an abnormal number of case reports. And it was investigated, and they found out that it did. But then there was a question of whether the human papilloma virus could cause chronic fatigue syndrome because there were a lot of case reports, and it turned out it didn’t. Or, frankly there were also a lot of vaccine-caused autism reported to VAERS, but the studies showed it didn’t. So you don’t actually learn anything from VAERS other than that this is something you might want to test.

The chickenpox vaccine is stabilized with porcine gelatin, and people can have a serious reaction to the gelatin, it’s real but rare. But that pales in comparison to what chickenpox did before the vaccine: four million cases per year, 10, 000 hospitalizations, between 70 and 100 would die.

Also, chickenpox lives silently in the body. It can reactivate later in life to cause shingles, it can reactivate early in life to cause strokes. We’ve seen a few children in my hospital with permanent paralysis from strokes caused by reactivated chickenpox. It’s a bad disease, it’s worth preventing.

A vaccine’s benefits should always dramatically outweigh its risks, and I think for every current vaccine we use, that’s true. With the oral polio vaccine, once we’d eliminated polio from this country, the vaccine’s risks outweighed the benefits, and we switched to the inactivated vaccine.

Why did the government take over responsibility for vaccine injuries in this country?

Because we almost lost vaccines for American children.

In the early 1980s, there were people who had the false notion that the whole-cell pertussis (whooping cough) vaccine could cause brain damage. There was a tremendous amount of litigation claiming that the vaccine caused epilepsy, mental retardation, SIDS, unexplained coma. There were tens of millions of dollars in awards and settlements for what was not a very big business for the pharmaceutical companies, and they gradually started getting out — until at one point we had only one company making whooping cough vaccine for children, and that company was about to get out. Whooping cough killed about 8,000 people per year before we started vaccinating, so the government stepped in, to basically protect these vaccine makers from direct litigation. We created the National Childhood Vaccine Injury Act (NCVIA) in 1986, and it did just that.

Can you address what your critics see as your conflict of interest, being both a vaccine advocate and a vaccine developer?

I came to the Children’s Hospital of Philadelphia in the early ’80s with an interest in working on rotavirus. It’s a virus [that causes severe diarrhea] that we know killed 500,000 people per year, I happened to live in a time when we could create a technology that could prevent deaths. I spent ten years working on trying to figure out how to construct virus strains that would protect children safely, I spend another fifteen years working on the research and development. I guess I’d ask critics what they would have had me do — if we had created strains in the lab that we thought could prevent rotavirus, at that point, we could have just said, “well, we figured it out,” and walked away. But the goal of this was to get a vaccine to children in the developing world where the virus kills 2,000 children a day.

Only pharmaceutical companies have the resources and expertise to make vaccines, and they will not do it unless you protect the technology with a patent. They won’t do it. We submitted for a patent then went to five companies and ultimately Merck was interested and we moved forward with the vaccine.

What should I have done differently? The logic of those who hate me is that I went into this to make money. But I can tell you I certainly never went into science to make money because no one in their right mind ever does. Certainly the motivation for making that vaccine was that rotavirus killed children, I mean I’ve *seen* children die from rotavirus. The reward is that the vaccine in now in Mali and Ghana and Bangladesh and Vietnam and basically eliminated the disease from Nicaragua. That’s the reward.

Did I make money off of it? I did. But it was like winning the lottery — it was a lot of money, and it was irrelevant to the work. I don’t feel badly about it, it’s not like I invented a method to freebase cocaine. I got lucky. I was in the right place at the right time and we were able to create a vaccine that saved lives.

But the money from the rotavirus vaccine — I’ve been out of that for a while. So why do I do this [vaccine advocacy]? Because it’s the right thing to do. Because children are getting hurt by all this misinformation. It’s the reason I went into pediatric infectious diseases in the first place — because kids get hurt.

Do you think part of the problem with vaccines backlash is that too few people in this country have first-hand experiences with vaccine-preventable diseases?

I think that’s exactly it. My parents had no problem vaccinating their children because they knew exactly what these disease could do, same with me; I’m a child of the ’50s, I had no problem vaccinating my kids either.

For young parents today, It’s not just that they don’t see them now, it’s that they didn’t grow up with these diseases. Vaccination becomes a matter of faith — but faith in who? In the government, in the pharmaceutical companies? There’s been an erosion in that kind of faith.

I spoke with (American Academy of Pediatrics spokesperson) Dr. Ari Brown during the 2010 pertussis epidemic; she said she sees people of grandparenting age disregard their personal experience in favor of what they see on Oprah and in the media. Have you seen this at all?

I think we’re abnormally influenced by celebrity. People will seriously consider Jim Carrey, Jenny McCarthy, Bill Maher, or Larry King as a source of health information, and that’s sad. It would be funny if it wasn’t so dangerous.

In your book, you mentioned that vaccines made it easer for women to enter the workplace.

You can imagine, when measles and mumps and German measles — all of which I had as a child — were common, my mother was staying home with each of the three of us as each of us got the diseases. She spent a lot of time at home taking care of sick children.

Vaccines have taken care of the fourteen main diseases that were causing a lot of illness and hospitalizations and death. There’s still a lot of infections out there, but they’re not quite as severe as the ones we’ve managed to prevent.

You’ve been criticized for having an opinion on autism causation when you’re not an autism stakeholder, and don’t specialize in children with autism. What’s your response?

That’s a fair question. But I would argue that Jenny McCarthy is also not an autism expert. Nor is J.B. Handley, nor are any of these other celebrities that you see on TV. But I have read the research on the subject since 1940; I’d say that I’ve read as much if not more than anyone else who is also “not an expert.” And as a scientist and clinician, I can form opinions that are reasoned and well-informed.

I’m never going to be an autism expert. The first thing I say when people ask me, “what do you think causes autism?” is that I’m not an autism expert, but I can tell you which studies are compelling. And I *am* a vaccine expert.

I don’t represent myself as an autism expert, and I think people like Jenny McCarthy need to be upfront about that as well. They’re experts in their own children, they’re not experts in autism.

How did you come to donate the profits from your books to the Autism Science Foundation?

I think Alison Singer is a hero. She’s the mother of a child, now a teenager, with severe autism. At first she chose to separate out MMR shots, she fed her child the gluten-free casein-free diet; she’s a smart gal who, like any parent of a child with autism, is desperate to do anything that would help — that makes perfect sense.

But then she became much more interested in looking hard at the science. For a time she worked with Autism Speaks — who have been frankly equivocal about whether or not vaccines cause autism and could have taken a stronger stance in support of the scientific data. That upset her enough to try and create her own foundation — to stands up to people who are mothers like her. It’s very easy for me to take a stand, I’m not a member of the autism community.

I think there’s a lot of good science that’s being done at major universities, and she’s trying to fund it, and I just think that’s just heroic. I like to reward people who are being heroes.

There has been a report that the current swine flu vaccine has been causing febrile seizures in some people. Could you talk about this, and  clarify the difference between febrile and classic seizures?

First of all, it appear that it possibly may have been associated with an increased risk of seizures due to fever, but that’s still to be determined. I wouldn’t say that’s solid yet.

There are about 150,000 children who suffer febrile seizures in this country; my daughter had a febrile seizures, actually associated with the DTaP vaccine. They’re hard to watch — my daughter’s was a grand mal seizure, it lasted for a couple of minutes, she was out of it for a couple of minutes. But the data are very clear — febrile seizures don’t cause sequelae, we know they’re benign. Anything that causes fevers in a child less than two at risk for febrile seizures can cause febrile seizures. Ear infections can cause febrile seizures, colds can cause febrile seizures, not just vaccines. One shouldn’t make more of this than it is.

Are vaccines constantly upgraded and monitored for safety and efficacy?

Yes, like no other medical product, including all the drugs you put into your body and certainly more than anything you’d get at the General Nutrition Center. We have a very well-tested, well-worn vaccine schedule.

What have vaccines done? They’ve helped us live decades longer than we did 100 years ago. There’s so much good that’s come from vaccines that it really hurts me to watch the way that people just dismiss them. We had five children [at my hospital] die from the novel H1N1 flu strain last year, none of them were vaccinated, all of them could have been saved by vaccinations. It’s not OK. It’s just not OK.


An abridged version of this interview was syndicated on