Wednesday, November 20, 2013

Pertussis

Someone from Vaccination Information Network (VINE) posted an article on FB, from Australia, apparently discussing pertussis in the US (1); The writer of the article was very much pro-vaccination and was blaming un-vaccinated for increasing rates of infection. Most of the posted comments were against vaccination for various reasons, and they posted links to various articles in support of their position:

A) Vaccinated persons are a reservoir of disease and are responsible for it's spread b/c
     they contract a milder case, are not recognized as a case, and spread it to others; whereas
     un-vaccinated individuals, if they contract the infection, have more severe symptoms and
     are recognized as a case (2)

B) Even the CDC acknowledges that the un-vaccinated are not necessarily the cause of the
     outbreaks (3); They also acknowledge the limitations of the vaccine in risk reduction (though
     they use the term "protection");

C) From an article about WC in Uinta County, WY (4):
           “In unvaccinated children there were 15 cases,” McClinton said. “Vaccinated children that were not up to date showed five cases. Children that were up to date showed 23 cases, fully vaccinated children showed 10 cases and adults had 11 cases for a total of 64 cases so far this year.”
It's hard to assess this w/o knowing the total population in this county (along with how many
in this county were vaccinated, un-vaccinated, partially vaccinated, and/or had a history of
having had WC whether vaccinated or not - oh, make that WC confirmed by lab testing!);
It is interesting to note that there were more cases among those who had any exposure to
the vaccine ("up to date" may mean recent receipt of vaccine though hx of partial vaccination,
fully immunized may mean receipt of all doses according to schedule, including being up to
date, and depending on their age it is reasonable to believe the adults had a hx of at least
partial immunization and may or may not have been up to date). The does not mention if
there were any deaths associated with WC.

An article on the Mercola.com site addresses a variety of issues with WC vaccine (and then
veers off on to a couple of related vaccine tangents), (5):

I think the last half of this quote (Dr. James Cherry's comments) is most interesting, and
quite honest -

Surprise! Whooping Cough Spreads Mainly through Vaccinated Populations
In 2010, the largest outbreak of whooping cough in over 50 years occurred in California. Around that same time, a scare campaign was launched in the California by Pharma-funded medical trade associations, state health officials and national media, targeting people opting out of receiving pertussis vaccine, falsely accusing them of causing the outbreak.
However, research published in March of this year paints a very different picture than the one spread by the media2.
In fact, the study showed that 81 percent of 2010 California whooping cough cases in people under the age of 18 occurred in those who were fully up to date on the whooping cough vaccine. Eleven percent had received at least one shot, but not the entire recommended series, and only eight percent of those stricken were unvaccinated.
According to the authors3:
"This first detailed analysis of a recent North American pertussis outbreak found widespread disease among fully vaccinated older children. Starting approximately three years after prior vaccine dose, attack rates markedly increased, suggesting inadequate protection or durability from the acellular vaccine." [Emphasis mine]
The pertussis (whooping cough) vaccine is included as a component in "combination" shots that include tetanus and diphtheria (DPT, DTaP, Tdap) and may also include polio, hepatitis B, and/or Haemophilus Influenza B (Hib). CDC data shows 84 percent of children under the age of three have received at least FOUR DTaP shots—which is the acellular pertussis vaccine that was approved in the United States in 1996—yet, despite this high vaccination rate, whooping cough still keeps circulating among both the vaccinated and unvaccinated.
So, as clearly evidenced in this study, the vaccine likely provides very little, if any, protection from the disease. In fact, the research suggests those who are fully vaccinated may in fact be more likely to get the disease than unvaccinated populations.
Why Do Pertussis Vaccines Fail Despite Claimed Efficacy?
Interestingly in a recent article published in the journal Pediatrics4, author James D. Cherry, MD, reveals that estimates for pertussis vaccine efficacy have been significantly inflated due to the case definitions adopted by the World Health Organization (WHO) in 1991, which required laboratory confirmation and 21 days or more of paroxysmal cough. All less severe cases were excluded.  He states:
"I was a member of the WHO committee and disagreed with the primary case definition because it was clear at that time that this definition would eliminate a substantial number of cases and therefore inflate reported efficacy values. Nevertheless, the Center for Biologics Evaluation and Research of the Food and Drug Administration accepted this definition, and package inserts of the US-licensed DTaP vaccines reflect this....For example, Infanrix... and Daptacel... have stated efficacies of 84% and 85% respectively. When less severe cough illness is included, however, the efficacies of these 2 vaccines decrease to 71% and 78% respectively. In addition, even these latter efficacies are likely inflated owing to investigator or parental compliance with the study protocol (observer bias)." Dr. Cherry lists eight potential reasons for why the efficacy of pertussis vaccines are overestimated:
Overexpectation of efficacy because of case definition.                                       Inflated estimates of efficacy because of observer bias.                                      Other Bordetella sp are the cause of similar cough illnesses.                            Lack of initial potency.                                                                                                    Decay in antibody over time.                                                                                Incomplete antigen package.                                                                                   Incorrect balance of antigens in the vaccine.                                                         Genetic changes in B pertussis
Whooping Cough is Cyclical Disease
B. pertussis whooping cough is a cyclical disease with natural increases that tend to occur every 4-5 years, no matter how high the vaccination rate is in a population using DPT/DTaP or Tdap vaccines on a widespread basis. Whole cell DPT vaccines used in the U.S. from the 1950's until the late 1990's were estimated to be 63 to 94 percent effective and studies showed that vaccine-acquired immunity fell to about 40 percent after seven years.
In the study cited above, the researchers noted the vaccine's effectiveness was only 41 percent among 2- to 7-year-olds and a dismal 24 percent among those aged 8-125.
With this shockingly low rate of DTaP vaccine effectiveness, the questionable solution public health officials have come up with is to declare that everybody has to get three primary shots and three follow-up booster shots in order to get long-lasting protection6—and that's provided the vaccine gives you any protection at all! 


Those who promote vaccination use the term "protection" - in this writer's estimation this
is too strong a term to be accurate. "Risk reduction" is more factual. The terms "protection"
and "risk reduction" are not inter-changable, they are not synonymous.

It seems that some vaccines may provide a measure of risk reduction, both in terms of not contracting the disease (if exposed), and/or contracting a milder case (if exposed). The question then becomes is the reduction in risk of disease worth the trade-off of possible long-term chronic disease associated with vaccination. Or, is it worth the unknown long-term safety profile of vaccines, since follow-up of adverse events if largely voluntary and there are few, to no, studies comparing the health of vaccinated populations with unvaccinated populations.

Most on either side of this divide (vaccinate or don't vaccinate) are passionate about their
positions ... because so many questions remain about effectiveness and/or safety, vaccination
should be voluntary, not mandatory.

Likewise, we should be determining how best to treat those who become ill in order to decrease morbidity and mortality.


Refs:
1) http://www.treehugger.com/health/vaccine-refusals-are-creating-whooping-cough-epidemics.html

2) http://vtdigger.org/2012/10/08/90-percent-of-whooping-cough-cases-in-vermont-among-vaccinated-children/

3) http://www.cdc.gov/pertussis/about/faqs.html#travelers (when accessed as of the date of
    this post, it had been updated as of Aug 28, 2013);

4) http://www.uintacountyherald.com/V2_news_articles.php?heading=0&page=72&story_id=6801

5) http://articles.mercola.com/sites/articles/archive/2012/07/30/whooping-cough-vaccine.aspx


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