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Vaccines and Infectious Diseases: Putting Risk into Perspective

American Medical Association Briefing on Microbial Threats, National Press Club Washington, DC

June 01, 2000

Carrie Schum - 202 973 5800

Remarks by Bruce Gellin, MD, MPH Executive Director National Network for Immunization Information

The topics we're discussing today have several things in common.
First, they all relate to infectious diseases. Second, they all present growing risks to health to people in the US and around the world. And third, they have been on the radar screen for some time but the blips seem to be getting brighter, so they can't be ignored any longer. It's time to focus and take action. Bioterrorism, emerging infectious diseases and microbes that are resistant to the best antibiotics and antivirals we can construct are the obvious topics for a session like this.

Less obvious, but potentially more of a threat to the public at large are the concerns, doubts, and misperceptions that increasing numbers of parents seem to be having about childhood immunizations.

Should these concerns, doubts, and misperceptions be left unaddressed, they could translate into a decline in the public's confidence about vaccines. If, as history has shown, a decline in public confidence leads to a decline in vaccine use, a number of diseases that are now well under control may re-emerge.

Vaccines are the most effective public health tool ever created. Life expectancy at birth has been extended by 30 years since 1900. And it's estimated that 25 of those 30 years are attributable to public health advances, especially vaccines.

We have achieved historic levels of immunization use in the community and record low rates of vaccine-preventable diseases. As a result of our immunization policies and practices in the U.S. we almost never see outbreaks of diseases like measles, polio, and diphtheria. Unlike parents of just a generation ago, today's parents do not experience the annual summer outbreaks of polio and the self-imposed quarantine that kept children from movie theaters, swimming pools, water fountains, and summer camps. But because parents no longer see, and don't fear that their child is at risk of being infected with these serious contagious diseases, we are risk of becoming a victim of our successful vaccination programs.

The coverage rates tell us that at present most parents continue feel that immunizations are the right thing for their child. At the same time, the research that the National Network for Immunization Information (NNii) has conducted over the past year shows that a significant minority of parents hold a number of important misperceptions that could ultimately erode their support for immunization.

NNii conducted a series of focus groups all across the country and also conducted a nationally-projectible survey with parents. We found that beneath the high immunization rate, there is another story. Parents have many questions about vaccines and our immunization policies. In addition to being unfamiliar with the diseases that vaccines prevent, they want to know more about the vaccines. Among their many questions: How are they made? What are they made of? Are they as safe as they can be? Why do they contain the components that they do (such as the mercury-containing preservative thimerosal and an immune-stimulating adjuvant that contains aluminum)? How are recommendations made? Who makes the recommendations?

These are all the right questions. The problem is that the system hasn't quite figured out how to get parents the answers they need. Parents are searching for answers, and many are either not finding the answers, or are getting information that's incorrect. As a result, many parents have significant misunderstanding about vaccines and our immunization programs and policies.

-Nearly 20% of parents we surveyed did not know how -- or even if -- vaccines are evaluated for safety and efficacy before they are licensed for use. They are unaware of the long road of vaccine development- taking as many as 10-15 years to complete the extensive laboratory work and clinical evaluations necessary to be even considered for licensure.

-One-fourth of parents we surveyed felt that their child's immune system could be weakened as a result of vaccination and almost as many felt that children were getting more immunizations than are good for them.

Except for those who live in bubbles, we are continually exposed to bacteria, viruses, allergens and foreign proteins as part of daily living. The immune system can handle hundreds of thousands, if not millions of such challenges. For example, depending on the particular virus, we may be exposed to up to 10 foreign proteins during a single episode of an upper respiratory infection. A routine 'strep throat' will present between 25 and 50 foreign proteins to the immune system. Modern vaccines are made of refined components of the organism, therefore actually present less of a challenge to the immune system than an infection would.

Since this survey was conducted last spring, prior to the withdrawal of the rotavirus vaccine and the discussions about further reducing exposure to thimerosal, the mercury-containing preservative in some vaccines that prevents contamination, it is likely that the level of concern among parents has only risen in the last year.

How did we get here?

The reasons why so many parents have important misunderstandings about vaccines are complex, but there are several key elements that we can all help to fix.

First, the scientific process can be confusing to those without scientific training. Even though the vast majority of the scientific data, and virtually all doctors, support the fact that vaccines are safe and effective, researchers are always looking for ways to make vaccines even safer. So, research on highly unlikely hypotheses about side effects of vaccines- the results of which often simply prove that there is no such relationship -- is often taken out of context. It's hard not to pay attention when a major network's anchor introduces a vaccine story on the evening news with, 'We were stunned to learn that questions have been raised about the way we vaccinate our children.' Unfortunately, the real finding often gets lost in the hype.

Recently, there was a lot of publicity surrounding a congressional hearing that examined the unproven hypothesis that the MMR vaccine is the 'cause' of autism. News coverage focused on stories of children who were diagnosed with autism soon after receiving their MMR immunization, leading viewers and readers to the obvious conclusion that there must be some relationship.

But the truth is different than it may have appeared. Because the concerns of parents ARE taken seriously by the medical community, and because ANY allegation of a relationship between a vaccine and a serious adverse event are considered worth investigating, the question of whether there is a relationship- in this case between the MMR vaccine and autism -is often studied by numerous researchers. In the case of MMR and autism -- other than a single small study which had serious flaws in its methodology and has been questioned by most other researchers -- no evidence of a link between the vaccine and autism has been found. Yet the safety and the power of the vaccine, the tremendous number of lives it has saved and disabilities that have been prevented by its use- that story was completely absent from most coverage.

Unfortunately, prevention just doesn't have the same news appeal. So, we in the medical community clearly need to do a better job of communicating both the benefits and the risks of vaccines and help all to better understand the diseases they so effectively prevent.

There is a lot of information out there about vaccines, but not all of it is scientifically correct and may feed into some of the parental misperceptions we're seeing. The Internet is one means by which both good and bad information is spread. The Internet has had and will continue to have a tremendous influence on the practice of and perceptions about medicine. Patients now come into doctors' offices with printouts from the Internet to discuss. An Internet search on 'vaccine safety' will lead you to one of the top sites that states: 'There is growing evidence that immunization may cause a large number of chronic diseases including diabetes, autoimmune diseases, allergies, asthma, cancers, and Gulf War Syndrome.' Another 'vaccine safety' site claims that the World Health Organization's neonatal tetanus immunization program is really a hidden birth control vaccine in disguise.

Even if the scientific data does not support these conclusion these sites usually contain powerful anecdotes from parents who believe their children were harmed by a vaccine. That's very believable to another parent. And these stories get spread from parent to parent, neighbor to neighbor until the hypothesis becomes a fact and people assume that they MUST be true. Just last week a television news program in Boston featured Laurie Flutie, the wife of NFL quarterback Doug Flutie, and the parent of an autistic son. She said that she heard so much about the MMR vaccine that she eventually figured it had to factor into her son's disability.

If we in the medical and scientific community don't speak out and do everything we can to get the best information to all who want and need it, more and more parents are going to continue to get the wrong messages.

How many times does history need to repeat itself?

We know that until a disease has been eradicated, a decline in immunization rate provides fertile ground for an outbreak. We've seen it happen over and over. In the 1970s and 1980s, large outbreaks of pertussis returned to those countries that rejected the pertussis vaccine because of concern about safety. The hypothesis that the MMR vaccine causes autism began in Britain. In the last few years, acceptance of the MMR vaccine has dropped significantly there. In an even more bizarre twist, some parents have become so fearful of the vaccine that they are hoping to get their children invited to a 'measles party' to intentionally expose them to the disease first. I wonder whether they know that 1/1000 children who contract measles suffer encephalitis, an inflammation of the brain, that can leave them permanently disabled?

The spark has now found dry timber in Ireland. An outbreak of measles that began in Dublin is now spreading around the countryside. At last report the case counts were above 700, including at least two deaths among the many with complications requiring hospitalization. Last year, the same thing happened in the Netherlands with over 3,000 cases of measles, and three deaths among the 500 who were hospitalized.

We don't have to look to other countries to learn these same lessons. A study in JAMA last year convincingly demonstrated that when measles returned to the community, those who had opted out of immunization were at a 35-fold increased risk of disease. While this example informs us of the magnitude of the effectiveness of the vaccine, perhaps the more important feature of this study is the finding that the outbreak that began among those who opted out of immunization spread into the community at large- including those few who had been immunized but in whom the vaccine didn't 'take.'

So while some parents say, 'Look, there's not much disease in my community, so my kid isn't likely to get sick. Why should I risk a complication from being vaccinated?' The answer is that the risks and consequences of getting these diseases are far greater than the small risks associated with the immunizations. The decision not to immunize one's child is a decision that places that child and other children in the community at greater risk.

There are many things we do to protect everyone in society that generally require that we all play by the same rules. You can ignore the four-way stop sign as long as others don't. But if others have the same idea, that intersection may not be such a safe place

So, what can we do? We need to put in place a process that ensures that the best information about immunization is available to all that need and want it.

The National Network for Immunization Information is taking the lead on this with our work. We were created as a partnership among the Infectious Diseases Society of America (IDSA), the Pediatric Infectious Diseases Society (PIDS), the American Academy of Pediatrics (AAP) and the American Nurses Association (ANA). We are channeling the expertise of these organizations into developing educational tools for doctors, nurses, and other healthcare clinicians. We have created a 'resource kit' to help providers communicate with their patients on vaccine-related issues, which we're going to distribute and make available on our web site later this year.

We are also creating a web site ( that will contain the latest scientific information on vaccine-related issues, for parents as well as for providers and policymakers- everyone who makes decisions about vaccination. Like medicine itself, our decisions about immunization should be based on the best available evidence, not anecdote and innuendo.

We believe that there is a pressing need to correct the misperceptions and help parents, policymakers and the media better understand why the experts and their doctors recommend that all children be fully protected through immunizations

Unless we make a concerted effort to provide the best information that we can, these misperceptions are likely to grow rather than diminish in the future. Our goal is to keep the iron lungs in the museums and the images of these diseases locked in black and white photos.


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Gangarosa EJ, Galazka AM, Wolfe CR, Phillips LM, Gangarosa RE, Miller E, Chen RT. Impact of anti-vaccine movements on pertussis control: the untold story. Lancet. 1998 Jan 31;351(9099):356-61.

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Measles, MMR, and autism: the confusion continues [Editorial]. Lancet 2000; 355: 1379.

Peltola H, et al. No evidence for measles, mumps, and rubella vaccine-associated inflammatory bowel disease or autism in a 14-year prospective study. Lancet. 1998; 351(9112):1327-8.

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Taylor B, et al. Autism and measles, mumps and rubella vaccine: No epidemiological evidence for a causal association. Lancet. 1999; 353 (9169):2026-9.

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