Dr. Robert Sears, son of the perhaps more famous Dr. William Sears (both pediatricians), has continued his father’s work of publishing popular books for parents. He wrote The Vaccine Book: Making the right decision for your child, published in October 2007. In it he advocates his Dr. Bob’s Alternative Vaccine Schedule. Much of his claims made in the book are repeated on his Ask Dr. Sears website.

In the latest issue of Pediatrics, Paul Offit, along with Charlotte Moser, write a detailed analysis of Dr. Bob’s alternative vaccine schedule, systematically reviewing Dr. Sears’ claims. It is essential reading for anyone interested in the popular vaccine controversy. Paul Offit also recently published his own book, Autism’s False Prophets, in which he goes into great detail about the history and science behind the claims by anti-vaccination advocates of the risks of vaccines, most famously the claim that vaccines are linked to autism.

Dr. Sears does not come off as a hard core anti-vaccinationist. I am still trying to figure out his perspective from reading his articles. It seems as if he is trying to be popular by straddling the fence, and offering what he thinks might be a reasonable compromise. For example, he writes on his site:

The bottom line is that more and more parents want options. If we don’t provide them with options they are comfortable with, more parents will opt out of vaccines altogether. We will then see more and more disease fatalities and complications.

Unfortunately, this is like trying to compromise between mutually exclusive positions, like young-earth creationism and evolution. It doesn’t work. Dr. Sears is left giving his readers, who will likely be comprised of many parents trying to decide whether or not to vaccinate their children, with partial information or misinformation. Offit and Moser do a great job of exposing this deception through misinformation.

If Dr. Sears is really interested in preventing disease fatalities and complications, he should provide his readers will sufficient information to make rational decisions – not partial information so as to create the impression of controversy and reasonable doubt where it does not exist.

I also disagree with Dr. Sears’ premise – that parents want options. I think what they really want is what is best for their children. They may think that options achieve this goal, but that is only because they are being assailed by contradictory information. They are being told over and over, on Oprah, Larry King, by celebrities, and a host of dedicated anti-vaccinationists that there is something to be afraid of. Spreading fear and doubt is easy, especially in the internet age. So it is understandable that parents want to allay their fears and be more confident that they are doing what is best for their children – which is their real goal (I am partially speaking as a parent myself).

What Dr. Sears accomplishes ultimately is to fuel the fire of that fear by spreading misinformation, or withholding from his readers the scientific information that has lead the scientific and medical communities to the recommendations they currently make. He also sets himself up as a guru – first by facilitating the spread of fear about vaccines, then offering himself as a solution – you don’t trust the Centers for Disease Control, the American Academy of Pediatrics, and the American Academy of Family Physicians (who all endorse the current vaccine schedule)? Don’t worry, good ‘ol Dr. Bob has the answer.

Also, as a physician, Dr. Sears’ approach runs contrary to my understanding of professional ethics. It is not our job to tell parents or patients what they want to hear, or to acquiesce to their desires, even if those desires are based upon poor information and reasoning. It is our job to tell patients or their parents our understanding of the scientific evidence, our best judgment as clinicians, and to give them strong recommendations when appropriate.

And finally, Offit and Moser convincingly demonstrate that Dr. Sears simply fails to understand the science.

I won’t review every point made in the paper – it is concisely written and well referenced, so those interested should read it for themselves.  But I do want to hit some highlights.

For me the most egregiously dishonest claims made by Sears were those concerning the alleged toxins in some vaccines. This is a critical issue because “the toxin gambit” has been a favorite of anti-vaccinationists. Sears plays into their hands, as Offit and Moser report:

Sears’ main argument for spacing out vaccines is to avoid giving infants too much aluminum at one time, writing, “When a baby gets the first big round of shots at two months, the total dose of aluminum can vary from 295 micrograms . . . to a whopping 1,225 micrograms if the highest aluminum brands are used and a hep B vaccine is also given. . . . These doses are repeated at four and six months.” Extrapolating studies of patients undergoing hemodialysis and severely premature infants to healthy newborns, Sears claims that these quantities might be unsafe. However, Sears fails to put aluminum exposure in context. By 6 months of age, infants typically ingest 6,700 micrograms of aluminum in breast milk, 37,800 micrograms in infant formula, or 116,600 micrograms in soy-based formula.

Failure to put a tidbit of information into proper context is the worst kind of deception, because it contains a truth but uses it to mislead. It is easy to scare parents by telling them that children may get exposed to 1,225 micrograms of aluminum in vaccines – but that fact is not so alarming when one learns that children will consume more aluminum through breast milk or formula. (Don’t worry, the amount from those sources is also well within safety limits). Toxicity is all about dose (a mantra Offit repeats) – and doses must be put into context.

Sears also plays the fence-sitting game when it comes to thimerosal, the mercury-based preservative in some vaccines (but no longer in the routine schedule). Sears writes:

“Do I think mercury is harmful? Yes. Do I think the amount in the old vaccines caused harm? I’m not 100% convinced one way or the other.”

What does “100% convinced” mean? This statement seems calculated to give the impression that it’s a toss up. In reality, the weight of the evidence is overwhelmingly against a link between thimerosal (or vaccines in general) and autism or any other neurodegenerative disorder. But Sears combines selective omission of the facts with a misunderstanding of how science works. More from Offit and Moser:

Using the scientific method, investigators form the null hypothesis. Good epidemiological studies are powered to reject or not to reject the null hypothesis. However, the scientific method does not allow investigators to accept the null hypothesis. Said another way, scientists can never prove never. The most that scientists can show is that 2 events are not associated statistically; scientists cannot prove that the events can never be associated statistically. In stating that it is “difficult to prove that there is not a connection,” Sears is suggesting the impossible.

Sears’ error is common – these kinds of studies can never prove zero risk. They can only set statistical limits on how large the risk can be.  When representatives from the CDC, for example, make statements to the effect that current studies have not found a link, but they cannot rule out a small risk, they are simply reflecting the proper logic behind epidemiological studies. But their statements are misinterpreted to mean that their is real doubt – that the door is still open for a significant risk. This kind of mistake is understandable from a non-scientist. It is inexcusable from a physician who has decided to go directly to the public with his personal views against the consensus of expert opinion.

Dr. Sears has also written and extensive rebuttal to Offit and Moser on his website. There is too much there for me to go over in detail – again, if interested, read the primary source. But after reading the entire rebuttal, here are some overall impressions. First, it seems that Dr. Sears is doing a lot of back-pedaling. In a way, this is a good thing. Perhaps he actually is clarifying his position, perhaps softening it.

Here are some examples. He acknowledges the current consensus that thimerosal is not linked to autism, but argues that he did not go over the evidence because he thought it was adequate to say that it is no longer in vaccines. In many cases Sears claims that Offit selectively quoted him and did not fairly represent his views – in other words, he actually agrees with Offit and simply did not make the claims that Offit says he did. And then sometimes, he flat out agrees with offit:

Once again, I am respectfully thankful for this constructive criticism. Dr. Offit is right. We shouldn’t view reported reactions in VAERS as actual vaccine reactions, and I shouldn’t have used such numbers to determine statistical risks. I do, however, point out in the book that we don’t know that VAERS reports are actual vaccine reactions.

Regarding aluminum, Sears simply says that this is a complex issue and at present we simply do not have the data to say that it is safe. I agree that there is room for more data on aluminum, but I disagree with his bottom line. He implies that the fact that aluminum in vaccines in injected means it cannot be compared to the dose of aluminum consumed orally. He has a small point – but only very small. There is no reason to think that aluminum is handled significantly differently by the body if injected rather than consumed by mouth. And the dose from vaccines is so small compared to overall environmental exposure, it is hard to believe that is has any significant biological effect. Still, a wider buffer of evidence would be welcome.

Although Sears went a long way to agree with the scientific consensus on many issues, I still think he fails to properly represent a rational risk vs benefit assessment of vaccines. He certainly did not make the case for his alternative schedule, nor provide any evidence that it is actually safer. But actually he is not claiming his schedule is superior to the standard vaccine schedule. For example, about the flu shot he writes:

As for the flu shot, here’s my opinion. Because mercury is a known neurotoxin, all the science in the world won’t convince many parents to give their baby a mercury-containing flu shot, especially when they have the option to get a non-mercury version. I completely agree with Dr. Offit’s statement that the science shows no evidence that the amount of mercury in a flu shot causes any harm. But I just don’t think that parents believe it.

And that is the core of his position – if we can’t convince some parents that vaccines are safe, let’s at least give them an alternative that they can feel more comfortable with so that their children get some vaccine protection. It is an interesting idea, but I think it ultimately fails. The problem is that we are waging a battle of public education. There is an organized and well-funded movement trying very hard to misinform the public about vaccines because they are ideologically anti-vaccine. There are those who are trying to counter the misinformation and educate the public as to why the vaccine schedule is what it is.

In the end, by trying to mollify some in the moderate anti-vaccine camp, he is contributing to the public’s misunderstanding of the issues, which is likely to cause more harm than good. Public health is a numbers game – if vaccine rates fall below herd immunity (as they have in some communities) outbreaks of vaccine-preventable diseases will (and have) occur.

So perhaps Dr. Sears means well, but is simply misguided and was a little sloppy in his arguments. Either way, his arguments needed to be deconstructed, and Offit and Moser did a fine job doing just that. I also consider forcing Sears to clarify many of his positions, admit a few errors, and state more clearly that he is in favor of the current vaccine schedule, a good thing. That may mitigate the use of his book and articles by the anti-vaccine crowd as support for their position.


Posted by Steven Novella

Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe, and the author of the NeuroLogicaBlog, a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also has produced two courses with The Great Courses, and published a book on critical thinking - also called The Skeptics Guide to the Universe.