OBJECTIVE. The objective of this study was to determine if children who contracted pertussis infection were more likely to have parents who refused pertussis vaccinations than a similar group of children who did not develop pertussis infection.
METHODS. We conducted a case-control study of children enrolled in the Kaiser Permanente of Colorado health plan between 1996 and 2007. Each pertussis case was matched to 4 randomly selected controls. Pertussis case status and vaccination status were ascertained by medical chart review.
RESULTS. We identified 156 laboratory-confirmed pertussis cases and 595 matched controls. There were 18 (12%) pertussis vaccine refusers among the cases and 3 (0.5%) pertussis vaccine refusers among the controls. Children of parents who refused pertussis immunizations were at an increased risk for pertussis compared with children of parents who accepted vaccinations. In a secondary case-control analysis of children continuously enrolled in Kaiser Permanente of Colorado from 2 to 20 months of age, vaccine refusal was associated with a similarly increased risk of pertussis. In the entire Kaiser Permanente of Colorado pediatric population, 11% of all pertussis cases were attributed to parental vaccine refusal.
CONCLUSIONS. Children of parents who refuse pertussis immunizations are at high risk for pertussis infection relative to vaccinated children. Herd immunity does not seem to completely protect unvaccinated children from pertussis. These findings stress the need to further understand why parents refuse immunizations and to develop strategies for conveying the risks and benefits of immunizations to parents more effectively.
Comments
Flawed Foundational Premise
Dear Sir,
Rewording the conclusion slightly it would seem that, "Herd immunity does not seem to completely protect (the 11% of) unvaccinated children from pertussis (which were given to them by the 89% of cases who were vaccinated)."
The body of the article talked about "ongoing endemic circulation" and "frequent asymptomatic infections" with the hope that adolescent and adult boosters might do something about both. If "herd immunity" exists, as the authors insist..., how can there also be " frequent asymptomatic infections" and "ongoing endemic circulation"?
The authors pin their hopes of improving this situation by repeatedly vaccinated all adolescents and adults.
However, the medical literature shows us:
1) That pertussis boosters do not improve any bactericidal activity in the vaccinated individuals: "we found no evidence that acellular vaccines promoted antibody-dependent killing by complement of enhanced phagocytosis by neutrophils" (1) which is a polite way of saying that the vaccines don't work.
As to why pertussis vaccine is not immunogenic, one must look at Dr James Cherry’s work:
2) "Of particular interest is the lack of a significant ACT antibody response in children for whom the DTP or DTaP vaccine failed.." (which is 89% of Kaiser cases)... "This induced tolerance is intriguing and may be due to the phenomenon called original antigenic sin. In this phenomenon, a child responds at initial exposure to all presented epitopes of the infecting agent or vaccine. With repeated exposure when older, the child responds preferentially to those epitopes shared with the original infecting agent or vaccine and can be expected to have responses to new epitopes of the infecting agent that are less marked than normal." (2)
There is a large body of medical literature that has been similarly ignored that clearly shows that individuals who gain their cellular and humoral immunity through the pertussis disease process, develop immune responses to ACT (adenylate cyclase toxin). When these individuals are reinfected, they are readily able to clear the bacteria and infection from their bronchials.
Conversely, as Dr Cherry stated, the immune systems of the vaccinated, because of their "original antigenic sin", ignore the ACT on rechallenge, because ACT is ONLY secreted as a product of natural infection, and is not an "ingredient" in the artificial vaccine manufacture process.
Therefore, in other words, the vaccinated adolescents and adults are unable to clear the bacteria, because their bodies learned the antibody immunity the wrong way, and therefore they also have no cellular immunity. The result is that they do spread frequent asymptomatic infections far and wide.
Is it a fluke, that when pertussis was primarily a childhood illness, rates of pertussis in adolescents and adults were rare?
The article finished with: "Future research should focus on the community impact of vaccine refusal and the risks to other vulnerable populations...."
A more scientific approach would be to swab Kaiser Permanente staff and patients regularly over the next 10 years, to find out just how far and wide “frequent asymptomatic infections” as a result of “original (vaccine) antigenic sin”, extends in the community at large.
The most important question which must be asked, is why have the authors chosen to demonize the parents of the minority 11%, and why did they not just focus on the well known flaws of the pertussis vaccine, and its inability to produce "herd immunity"?
Hilary Butler.
(1) Weingart, C.L. et al 2000. “characterization of bactericidal immune responses following vaccination with acellular pertussis vaccine in adults.” Infect Immun, 68(12):7175-9. PMID: 11088351. (2) Cherry J.D. et al. 2004. “Determination of serum antibody to Bordetalla pertussis adenylate cyclase toxin in vaccinated and unvaccinated children and in children and adults with pertussis.” Clin Infect Dis 38(4):502-7. PMID: 14765342.
Conflict of Interest:
None declared
Obfuscation and misinterpretation?
This paper clearly states that "Patients were classified as confirmed [pertussis] cases if they had a medical chart-verified positive PCR test OR a positive culture for B pertussis" (emphasis mine).
The authors note that both PCR and laboratory culture results were recorded for each subject, so given that PCR by itself is generally considered insufficient for diagnosing pertussis [1], one has to wonder why the authors did not state what proportion of "patients" were classified solely on the basis of a positive PCR test. I also must ask, why did Pediatrics not require this data before publishing this study? Without this information, it is impossible to evaluate this study.
Furthermore, note that when the authors hypothesize that "parents who refuse vaccinations may be less likely to bring their children to medical attention for acute illness", they include a reference to lend credibility to their assertion. However, the referenced study itself does nothing more than pose the same hypothesis [2]:
"Moreover, this tendency on the clinicians’ part may have been offset by the POSSIBILITY that parents of exemptors might have been less likely than those of vaccinated children to seek traditional medical care that involved laboratory testing." (emphasis mine)
This is disingenuous at best.
Some additional issues with this study:
* No differences in pertussis symptoms, duration of symptoms, or sequelae were found between vaccinated and unvaccinated children. This is highly significant, in that it goes against claims by the CDC that vaccines, even when they fail, provide some degree of protection. This finding should be highlighted in the abstract.
* If 11% of pertussis cases are associated with vaccine refusal, then 89% of cases are by definition associated with vaccine FAILURE, correct?
* The finding that unvaccinated children presenting to a clinic with URI were > 3 times more likely to be tested for pertussis than vaccinated children is extremely important, and in my opinion very understated in this paper as a potential source of bias. It also calls into question the validity of all passive surveillance of disease incidence relative to vaccination status, does it not?
* This study found that vaccinated children were twice as likely to visit the clinic for an URI than unvaccinated children. The authors' interpretation is very telling, in that they simply assume that this finding must be a reflection on the behavior of vaccine refusing parents. Did it ever occur to them, or to those reviewing this manuscript, that the relevant variable here might very well be vaccination status? Just recently a study found that children given the influenza vaccine were more likely to require hospital visits. [3]
So there are many issues with this study, but the lack of data on how many pertussis cases were identified based on PCR test alone makes this study difficult to interpret. If a majority of these case classifications were based on PCR alone then in my opinion the results of this study become invalid.
Sincerely,
David Foster
1. http://www.uhl.uiowa.edu/services/respiratory/pertussisfaq.pdf
http://www.uhl.uiowa.edu/kitsquotesforms/bordetellapertussiscollectioninstructions.pdf
http://www.thefreelibrary.com/Pertussis+PCR+testing+at+the+Vermont+Department+of+Health+Laboratory. -a0173513512
http://www.nj.gov/health/cd/documents/Pertussis_Outbreak_Control_Guidelines.pdf
http://www.epi.alaska.gov/bulletins/docs/b2005_27.pdf
http://query.nytimes.com/gst/fullpage.html?sec=health&res=9501E7DB1F30F931A15752C0A9619C8B63&fta=y&pagewanted=all
2. http://jama.ama-assn.org/cgi/reprint/284/24/3145?ck=nck
3. http://www.sciencedaily.com/releases/2009/05/090519172045.htm
Conflict of Interest:
None declared