Get Up To Speed on the Vaccine Debate

Since publishing our profile of Amanda Peet, we've gotten lots of reader feedback about her pro-vaccine stance. Many of you feel she was harsh in her depiction of people who don't vaccinate their children; others applaud her for advocating vaccines as a public health benefit. Here, we interview two doctors on opposite sides of the debate (one of them is Paul Offit M.D., the doctor whom Peet consulted when she wanted to learn about the vaccination issue).

PAUL OFFIT, M.D.

Why do you think staggering vaccinations is not a good idea?
There is no data to suggest why we should delay or space out vaccines. We give 14 vaccines by two years of age, which can mean up to 5 shots at one time, and I can understand why that feels overwhelming. But vaccines are very well tested. Every time a new vaccine comes onto the market you have to do something called concomitant-use studies to show that your vaccine, when given either alone or in concert with the existing schedule, doesn't affect the safety and efficacy of other vaccines and that the other vaccines don't affect your vaccine.

The problem is, when you separate or delay or space out vaccines, you're only increasing the period of time during which children are susceptible to certain preventable diseases. And that's never to your advantage. And further, the schedules that people want to use and test out on their own, those haven't been tested.

What do you say to parents who are concerned about the increased schedule of vaccinations?
The schedule has increased because we've discovered more vaccines. That's why we're healthier; that's why we live longer. And the antivaccine camp will say, "Well, we've just traded infectious diseases for chronic diseases such as multiple sclerosis, arthritis"—but [that's not correct]. The main difference is that with vaccines we're living longer. I think where people get confused is when you have a 4-month-old and you watch five shots get lined up on the table. I think any reasonable person is going to recoil at that. But the fact is, if you take all the immunological components in vaccines—like a bacterial protein, or a viral protein—and add them up, you get about 150. That's fewer than what was in the smallpox vaccine alone 100 years ago.

Have levels of the preservative thimerosal (ethyl mercury) increased overall in the past 25 years as a result of the increased vaccination schedule?
The birth of thimerosal vaccines came in the late 1930s. Before that, we used primarily multidose vials, which required preservatives. Basically we've now moved from multidose to single-dose vials, which don't require preservatives. Live viral vaccines also don't require preservatives. Throughout the 1980s and 1990s the numbers of vaccines increased, and so levels of thimerosal did get as high as 187 micrograms. In 1999, as a precautionary measure, the American Academy of Pediatrics spearheaded a movement to try to eliminate thimerosal from vaccines.

By 2001, thimerosal was gone from all but one preparation: the flu vaccine. Not only have the rates of autism continued to increase but, more important, we now have six excellent epidemiological studies [that compared the populations who had thimerosal vaccinations to the ones that didn't], that show that thimerosal does not increase the risk of autism. The studies were done in this country, Denmark, Canada, the U.K., and others; there were many different populations.

What about claims that vaccines contain antifreeze and dangerous levels of aluminum?
Vaccines do contain aluminum in the form of aluminum salts, which typically enhance the immune response and enable you to give fewer doses and a lower quantity of immunological components. But again, if you look at the data on the recommended safety levels of aluminum—which is not a heavy metal, despite what people think, it's a light metal—it's eliminated very quickly from the body.

Vaccines don't contain antifreeze. One particular vaccine contains one component of antifreeze, propylene glycol. Propylene glycol is in many products we use, including salad dressing.

How can parents feel confident that doctors are unbiased or uninfluenced by pharmaceutical companies?
The conflict of interest issue is off the point. I go through this all the time—because I am the co-inventor of a vaccine, people think I must be evil. The reason we did the work is because it saves lives. But it's true that I also make money out of it—as a co-inventor, I'm a co–patent holder, and as a co–patent holder of a revenue-generating product, I make money off this. But it's certainly not the reason I did it, and it's not the reward. It's not like I co-invented a method to freebase cocaine—I mean, vaccines are a good thing.

All of the recent scientific studies have found no link between vaccines and autism, and a majority of the authors of the original Lancet paper have repudiated their findings. So why is there still so much controversy over vaccine safety?
Well, we're now at hypothesis number three. The first hypothesis was that MMR [the measles, mumps, and rubella vaccine] caused autism. People panicked; parents of more than 100,000 children didn't get the MMR vaccine in the U.S.; and there were major outbreaks of measles in the U.K. that caused deaths. Now there have been about ten studies that have shown no difference: Get the MMR, don't get the MMR; autism rates remain the same. So that was hypothesis number one. Hypothesis number two was that it wasn't MMR that caused autism, it was thimerosal. And there were six studies that showed that that wasn't true. So then you look at hypothesis number three, which is where we are now, and it's that kids are getting too many vaccines. This is much, much harder to study. Maybe you could take kids who are homeschooled, who aren't getting vaccinated. They'll probably do these studies, but if they don't show anything, we'll move onto something else.

There's a hypothesis that in a small subset of people with a genetic predisposition, like a mitochondrial disorder, vaccines and other environmental factors may trigger autism. What's your take on this theory?
Here's why I think that that's not it. Epidemiological studies are actually quite powerful. For example, in 1976 there was an influenza outbreak, and we made 40 million doses of the vaccine and distributed it throughout the country. The vaccine was found to cause Guillain Barre syndrome, a nervous system disorder, in 1 in 100,000 people—about 400 people.

When the Rotashield vaccine was given to about a million children, a very rare intestinal blockage affected 100 children. [The ability of these studies to isolate those numbers]—that's pretty powerful.

You have this omnibus autism proceeding going on in federal-claims court in D.C., where parents of 5,000 children say that vaccines caused autism. But if this were right, it would easily be found in retrospective studies. We're saying that autism occurs in 1 in 150 children. If mitochondrial enzyme deficiencies accounted for one percent of that, you would find it in epidemiological studies.

So what do you think does cause autism?
Within autism, there's a broad spectrum [of symptoms and severity], but it's clearly genetic. When you look at the so-called family studies, such as twin studies, and see what the incidence of autism is in one twin if the other has it, in identical twins it's over 90 percent; in fraternal twins it's less that 10. But I certainly believe that the environment can interact with genes in ways that affects their development—if you define environment as anything other than genetic, not just environmental toxins, which is what many people leap to.

Next Page:  Q&A with Jay Gordon, M.D.