Colorado Researchers Document Consequences of Failure to Vaccinate Children for Pertussis

Below is an article I wrote, along with my friend, Reg Finger, MD, MPH, on the impact that the anti-vaccine zealots are having here in Colorado. The article appeared in a publication of the Colorado Academy of Family Physicians, the CAFP News. It’s written for professionals, but my readers here will enjoy it.

It should not be a surprise to family physicians that a case-control study of children contracting a vaccine-preventable disease will find them less likely to have received recommended doses of the vaccine on time than those children who did not become ill. And now we have Colorado data to prove it.

In September, researchers from Kaiser-Permanente in Denver, in collaboration with co-investigators in five other states and from CDC, published results of their pertussis study in JAMA Pediatrics.[1] Children undervaccinated with DTaP by 3 doses were almost 20 times and by 4 doses almost 30 times (and that’s not percent!) more likely to be diagnosed with pertussis than children whose vaccines were up to date.

These findings deserve note here in Colorado for several reasons:

  • First, due to a variety of clinical and epidemiologic factors, pertussis has persisted in the face of routine immunization longer and more “successfully” than any other vaccine-preventable disease. Each of the others (measles and mumps in particular) occasionally strikes with a vengeance when immunization is neglected. However, pertussis is always around somewhere and the price for failure to vaccinate will likely be paid sooner rather than later. Pertussis outbreaks in Denver, Boulder, and Greeley in the last two years have disrupted many families and commanded plenty of media attention.[2],[3]
  • Next, it is clear that many of our state’s children and adults remain unvaccinated. In the latest (2011-2012) National Immunization Survey results published on line by CDC,[4] Colorado ranks 41st among states for percent of young children having received the four recommended doses of DTaP vaccine on time. We are four percentage points below the national average.
  • Finally, it is very appropriate that since the publication of this study, one of simple but robust design and with results too extreme to ignore, was led by authors from our own state, that our statewide professional publications should acknowledge it.

Recently, epidemiologists figured out that one reason pertussis refused to go away was that it was “slipping around” the immunization schedule by infecting adults, parents and grandparents especially, who then transmitted the infection to infants too young to be immunized, sometimes with fatal results. At that point, pertussis vaccine recommendations were changed to include adults as well as children.[5]

All this leaves us with this question: Why are family physicians and the parents in our practices not more consistent in getting children and adults vaccinated, and what more can we all do about it than we have already?

Currently, these steps are being taken in Colorado:

  • We make the vaccine available widely in clinics throughout the private and public sectors;
  • We have a statewide immunization registry[6] to make it easy to find out who needs the vaccine and when;
  • We enforce school and preschool immunization requirements[7], and
  • We continue to emphasize in the media at every turn that vaccines are important and that proposed objections to the safety of routine immunizations have been found to lack merit.

We did not write the previous paragraph because we have a compelling list of answers to put in front of you. Physicians, public health professionals, and child advocates have been working at this for a long time and know that the most workable way to get a family into a health professional’s office for immunizations varies with each family.

However, considering for a moment just one-birth year’s worth of children, about 65,000 in Colorado, we see that each percentage point represents about 650 children. That means that 650 unique solutions have to be found in order to improve our state’s standing by one point.

It is a challenge that can be met if every individual, family, and health professional does his or her part. Coloradans deserve no less.

2013: Worst Year for Measles in 15 Years

Dr. Anne Schuchat, director of the National Center for Immunization and Respiratory Diseases, is emphasizing the important role vaccines play in combating outbreaks of measles and other diseases, while announcing that “2013 already is one of the worst years for measles in more than 15 years.”[8]

What’s the main cause? Dr. Schuchat says, “Clusters of people with like-minded beliefs leading them to forgo vaccines can leave them susceptible to outbreaks when measles is imported from elsewhere.” Dr. Schuchat pointed out, “This is an extraordinarily contagious virus.”[9]According to the CDC, at least 82 percent of the cases involved patients who had not been vaccinated,” while the vaccination status of another 9 percent of those infected was not known.[10]

When it comes to vaccines, can children get “too many, too soon”?

It’s been reported that anti-vaccine zealot Jenny McCarthy is joining ABC’s “The View” as a host.[11] She is well-known for her false and misleading claims that vaccines cause autism, including her claim that when it comes to vaccines that children get “too many, too soon.”[12]

While it is true that the recommended vaccination schedule exposes children to 5 live attenuated or altered organisms and 21 different antigens by age six, is this really “a lot”? Does this antigenic load put an enormous burden on the immune system sending it spiraling out of control to damage some of our children? Does this explain the increase in autism diagnoses?

The simple answer: absolutely not. Perhaps one of the best videos we’ve seen to explain this to parents has been produced by Academic Earth. If you can’t view the video, here’s the transcript:

Too many, too soon!” is the favored battle cry of the anti-vaccine crowd. Too many shots, too many antigens, too close together.

By age 6, the recommended vaccination schedule exposes children to 5 live attenuated or altered organisms and 21 different antigens.[13][14] Is this a lot? Does this put an enormous burden on the immune system sending it spiraling out of control to damage our children? Let’s find out.

It has been estimated that humans can generate about 10 billion different antibodies, each capable of binding a distinct epitope of an antigen.[15] Actual estimates of antibody specificities in an individual, due to exposure to various germs and other foreign materials, range between 1 million and 100 million.[16]

We cannot say with absolute certainty how many antigens the average human is exposed to by age 18, but let’s say, as an argument, that you’ve had most of your antigen exposure by that age. Assuming total exposure is around 1 million antigens, this equals 152 unique exposures per day. Under this conservative estimate, by age 6, the vaccine exposure would account for 0.006% of the total antigen exposure of the child.

If a child is exposed to 100 million antigens by age 18, the rough maximum, we’re looking at 15,520 unique exposures per day. By age 6 that would be nearly 34 million antigens, and the vaccine schedule would account for 0.00006% of exposure.

No matter how you slice it, the vaccine schedule represents a miniscule exposure to antigens and organisms compared to what people encounter as part of life. Worrying about the exposure from the vaccine schedule is like worrying about a thimble of water getting you wet while swimming in an ocean.

Reginald Finger, MD, MPH, is a public health expert and researcher, as well as a former member of the CDC’s Advisory Committee on Immunization Practices (ACIP). Walt Larimore, MD, DABFP, FAAFP, a well-known author and medical journalist, works with Concentra Medical Clinics and volunteers at Mission Medical Clinic in Colorado Spring.


[2] Stutzman E. Rumors, reluctance, and herd immunity: Whooping cough outbreak. Boulder County’s The Daily Camera 2012(Aug 24).

[5] Finger RF, Shoemaker J. Preventing Pertussis in Infants by Vaccinating Adults (editorial). Am Fam Physician 2006; 74(3):382.

[6] Colorado Immunization Information System. Colorado Department of Public Health and Environment.

[8] Stobbe M. US Measles Tally Already Among Worst in 15 Years. The Associated Press 2013(Sep 12).

[14] Crislip M. The Infection Schedule Versus the Vaccination Schedule. Science-Based Medicine 2008(Nov 21).

[15] Fanning LJ, Connor AM, Wu GE. Development of the Immunoglobulin Repertoire. Clin Immunol Immunopathol 1996;79(1):1-14.

[16] Problem 5: Antibody diversity. Immunology Problem Set. The University of Arizona’s The Biology Project 2000(Nov 10).

Here are some of my other blogs on the topic:

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