Tuesday, September 20, 2011

Disappointing Coverage of Pertussis Vaccine Findings

Pertussis has been in the news a fair bit recently. Actually, it's the vaccine against pertussis that has garnered a lot of attention after a recent presentation and study from the 51st Interscience Conference on Antimicrobial Agents and Chemotherapy. The presentation, Marked Acellular Pertussis Vaccine Failure in 8-14 Year-olds in a North American Outbreak, suggests that immunity from the pertussis vaccine can wane in as little as 3 years, covered a study by Kaiser Permanente Medical Center under the supervision of Dr. David Witt.


The story has been picked up by a lot of media outlets, such as the Associated Press and subsequently regurgitated in places like ABC News, The Boston Globe and The San Francisco Chronicle. While the story raises some valid questions, there are some problems with how it is being presented.

First and foremost, the spin on the study is that the waning immunity from the pertussis vaccine is somehow new and shocking, something that we did not know about before. We've know since at least 2005, if not earlier, that immunity from the vaccine ranges from about 4-12 years. Similarly, immunity following natural infection with Bordetella pertussis, the bacterium that causes whooping cough, wanes in about 4-20 years. This is not news. It's something we have known for a while, yet not one of the news stories covering this subject mentions the fact, nor does it seem that the Witt et al. acknowledge this fact. From the abstract, the authors state that "acellular boosters appear to be ineffective after 3 years." This seems to overstate things a bit. Are the boosters truly ineffective, or does the efficacy simply start to wane?

Speaking of efficacy, it is unclear from media reports and the presentation abstract whether the researchers controlled for the failure rate of the vaccine. According to the CDC Pink Book chapter on Pertussis, acellular pertussis vaccines have an efficacy of around 80%-85% (PDF). That means that for every 100 individuals who complete the vaccination series, there will be around 15-20 who will not develop immunity. The selection methods, picking anyone with a positive PCR for B. pertussis, may be sufficient to control for this, but it is something that is worth mentioning, to put things in context.

This brings us to a couple other issues: case definitions and population selection. Notably, the methods used by the authors to select cases for their study differ from the case definitions used by the CDC, which include the duration of cough and additional symptoms in addition to a positive PCR. It is possible for PCR to give a false positive, especially if samples are taken in a location which also administers or handles pertussis vaccines. The technique only requires a piece of genetic material, not the entire bacterium, to produce a positive result. It is therefore possible that PCR alone may indicate a patient is infected with pertussis when they actually have a different respiratory illness. It is not clear how Witt et al. controlled for false positives from the PCR.

What was also missing from both the study and the media reports was a sampling of the population who had received the vaccine in a similar timeframe to the 132 clinical cases identified, who had been exposed to the bacteria, yet who did not develop clinical illness. We know that in the 132 cases in the study, immunity waned in as little as 3 years. However, the level to which this represents the community at large is unknown. How many individuals were exposed to pertussis but remained immune thanks to the vaccine?

These are all very important questions which were not even glossed over in media accounts. They simply weren't considered at all. The down side of this is that the media reports play into anti-vaccine propaganda that the vaccines "don't work" or that because they may provide only short-term immunity, then "what's the point?" The acellular pertussis vaccines do have shortcomings; immunity can wane and efficacy is not as good as other vaccines. There is certainly room to improve it in terms of both efficacy and duration of immunity. However, the fact remains that it is pretty effective and immunity can last for much longer than 3 years. It has had a tremendous impact on overall pertussis rates, reducing incidence of disease by nearly 80% since it was first introduced (see the Pink Book link above). The triumph of this vaccine has meant that significantly fewer infants die from this disease and non-fatal complications are far less common in the population at large.

In the end, I have been extraordinarily disappointed in the media coverage of the new study. It has lacked basic investigation into what we already know of the science behind the vaccine and ignored the nuance of the subject. To all the science journalists out there, let's try to raise the bar a bit.

11 comments:

  1. It seems to me that your disappointment is not due to any part of this study that was not correct (if it were, you have no mentioned that) but rather, because this study questions the effectiveness of the pertussis vaccine - something which is taboo amongst many pseudo-skeptics.

    The fact is that whether vaccine coverage is shown to be high or low, the incidence of whooping cough is increasing and a majority of those contracting the disease are fully vaccinated.

    The fact is that many studies are indicating that use of this vaccine is not only useless at preventing the occurrence of pertussis, but may be responsible for the emergence of more virulent strains of pertussis bacteria, leading to an increase in deaths amongst infants.

    And the fact is that boosters have been shown to provide an even shorter duration of antibody production (not to be confused with immunity since high levels of antibodies don't necessarily correlate with protection from infection) than the initial series of vaccination.

    The pertussis vaccine is not working. It is very possible that it's responsible for increased serious illness - aside from any adverse reactions the vaccine has been associated with. It is time to be more open about the failings of this shot and to remove any mandates in place - allowing parents to be fully informed and to make their own independent vaccination decisions.

    Meryl Dorey
    Australian Vaccination Network, Inc

    ReplyDelete
  2. Todd, you should be honored. The Grand Dame of anti vaccination lunacy herself is here, all the way from Australia. Funny how a study in California interests her so much. Could it be that it is ammunition for her anti vaccine propaganda machine?

    Notice how she did not counter any of your thought out, reasonable questions and explanations. Anti vaccine to the core, that old Meryl.

    It's simple math, really. The vaccine is given to millions and millions don't get pertussis. The vaccine is given to few, and millions get pertussis. History shows us this. The mathematical and epidemiological concepts of herd immunity, cocooning, etc., eludes some people, I guess.

    Just watch, when the authors of this study suggest that more boosting is needed, as they surely will, Meryl et al will disavow ever supporting these findings.

    ReplyDelete
  3. The AVN as usual has it wrong. Not just a bit wrong but completely wrong. The "facts" presented by the AVN above are not facts, worse they are demonstrably wrong.

    Let's take the very first "fact". That the majority of cases involve the fully vaccinated. The vast majority of cases involve adults who have not had any whooping cough vaccination for more than ten years. This is "not full vaccinated" and that their immunity is now compromised is well documented. "booster" shos are required to maintain immunity throughout your life. However in general pertussis is not life threatening to adults.

    Furthermore the majority of caes that do involve life threatening outcomes occur amongst those that are young and not fully vaccinated.

    There is however a fact that does need repeating here. Meryl Dorey and the AVN have been found to be a threat to the public health, they have been found to give misinformation, to wrongly and or selectively quote research , and to be totally anti vaccination. The Health Care Complaints comminission as well as the the Office of Liquor and Gaming have both filed adverse outcomes about the AVN.

    Their credibility is nil. Their danger is real.

    ReplyDelete
  4. Wow. Meryl herself visiting my wee li'l blog. I must've struck a chord.

    Meryl, apparently your reading comprehension is just as bad as your reasoning skills. Perhaps you just skimmed my post, rather than actually reading it for content, or else you would have noted where I mentioned that the fact that the vaccine immunity can wane in 3-4 years is well known and this study doesn't reveal anything new.

    You might also have missed where I did, in fact, question some of the methods and findings of the study, or at least the fact that the conclusions drawn are not exactly supported by the evidence.

    But then, you and truth have never exactly been on a first-name basis. Thanks for stopping by, though.

    ReplyDelete
  5. Meryl,

    Reading for comprehension 101.

    Todd's dissapointment was largely due to:

    - the way the study was reported in the media,

    - the "case definitions and population selection" used

    - the absence of "a sampling of the population...who had been exposed to the bacteria, yet who did not develop clinical illness."

    I don't know of anyone in the skeptic movement against the questioning of any medical practice. The opposite is true, it's the constant questioning that allows science to progress. When 132 young people suffer from the outbreak of a dangerous disease it is proper to ask why the efforts to prevent this have failed. This does not mean you ingnore the billions of people who do not get what was once a more prevalent illness.

    ReplyDelete
  6. reasonable_hank couldn't post this for some reason, so I'm putting it up for him in two parts:

    Meryl Dorey says:

    "It seems to me that your disappointment is not due to any part of this study that was not correct (if it were, you have no mentioned that)"

    - um...yes he did. Maybe you were reading Natural News and decided to comment on here by mistake? Y U NO mention that?

    "The fact is that whether vaccine coverage is shown to be high or low, the incidence of whooping cough is increasing and a majority of those contracting the disease are fully vaccinated."

    - In areas of low vaccination coverage like, say, the Northern Rivers of NSW, where you live and breathe, which has the lowest immunisation rates in Australia, disease rates are higher. Write it off as coincidence hey, Meryl?

    - The majority of those catching the disease are adults: Pertussis vaccine coverage rate of 11.3% at last count. Coincidences...what are you gonna do?

    "The fact is that many studies are indicating that use of this vaccine is not only useless at preventing the occurrence of pertussis, but may be responsible for the emergence of more virulent strains of pertussis bacteria, leading to an increase in deaths amongst infants."

    - We're going to need a citation for that. Not whale.to if you can help it.

    - The study itself, as quoted in recent articles, which are light on in some pertinent reporting, says that the study looked at 15,000 children. 132 got whooping cough last year. 80% of those were vaccinated. So, 105 vaccinated kids out of 15,000 got whooping cough? That seems like pretty good effectiveness for something that is "useless" which is causing "more deaths in infants".

    - The author, himself, "also found that shots work great in the short term. Rates of whooping cough dropped dramatically after kids were age 11 and 12, when many get the booster shot."

    http://www.optimum.net/News/AP/Article?fmId=53822480

    So, the need for boosters is confirmed by the author? Inconvenient that one.

    ReplyDelete
  7. Here's part 2 of reasonable_hank's comment:

    "the fact is that boosters have been shown to provide an even shorter duration of antibody production (not to be confused with immunity since high levels of antibodies don't necessarily correlate with protection from infection) than the initial series of vaccination."

    - Nirvana Fallacy number 1. Because "high levels of antibodies don't necessarily correlate...", that is skewed to mean that this is always the case; therefore, to quote Meryl Dorey "vaccination does not equal immunisation" ever! I would like Meryl to explain this intricacy of immunology to all of us.

    "The pertussis vaccine is not working"

    - Nirvana Fallacy Number 2. You're racking them up Meryl. But, we expect that. Here is a little insight: no one claims that vaccines are perfect. Just because something is not perfect (and it has been made quite clear that Todd and everyone else are stating this, unequivocally), does not mean it is useless. Nuance, you have no friend in Meryl Dorey.

    "It is very possible that it's responsible for increased serious illness"

    - Citation. Also, it is quite possible that I have a Dragon in my garage: wanna see it? If you follow any creationist threads, Meryl, you might see that quote used everywhere. The Argument from ignorance is a creationist favourite. Funny you should rely on it so often, being, you know, a woman of science and all.

    "aside from any adverse reactions the vaccine has been associated with"

    - Leaving aside your grammar, of which one could easily make a point; can you please list these adverse reactions? Protip: SIDS, autism, ADHD are not allowed anymore. Nor is that foulest of quotes you invented to defend baby murderers and assaulters "Shaken Maybe Syndrome". List the valid and acknowledged AEFI, and you may be taken seriously. SRSLY.

    "It is time to be more open about the failings of this shot and to remove any mandates in place"

    - I'll let the non sequitur pass by without even referring to it this time. No probs.

    - The failings of the aPertussis vaccine are acknowledged, and research is continuing on making a better one. Science is a bitch like that.

    "allowing parents to be fully informed and to make their own independent vaccination decisions"

    - From the self-appointed President of an anti-vaccination network that exercises the severest of censorship I have witnessed, whenever anyone posts accurate, reputable information to any of your fora? You do not wish anyone to be "fully informed". Your narcissism prevents you from ever stating that you have erred. You have never retracted a breathtakingly incorrect statement. By "informed" you mean: "informed by Meryl Dorey... now buy my Scientology DVDs, available now in the AVN shop at the low price of...doctors are lying to you...buy this crank cancer cure DVD NOW..."

    "Australia's Leading Expert on Vaccination" folks (self-appointed).

    ReplyDelete
  8. Let's do some basic arithmetic shall we?

    132 children were reported with pertussis out of 15,000. 80% of them were vaccinated.

    That means 106 vaccinated and 26 unvaccinated.

    According to Bay Citizen http://www.baycitizen.org/data/immunizations/ Marin County kindergarteners have a vaccination rate of 83%. Not valid to extrapolate that too far, but ok for our napkin calculations here.

    So 83% of 15,000 is 12 450 vaccinated children, and 2550 unvaccinated children.

    This means that 106/12 450 vaccinated children got pertussis, which is 0.85% or a rate of 1 in 118 children.

    26/2550 unvaccinated children got pertussis, which is a rate of 1% or 1 in 96 children.

    This means unvaccinated children got pertussis at a rate 1.2 times higher than vaccinated children. In other words, unvaccinated children had a worse chance of staying healthy.

    But wait, there's more! Not vaccinating correlates with a high rate of distrust of doctors. As Meryl would know, because she repeatedly states that she cannot recommend doctors and uses chiropractic and homeopathy for her own family. But only doctors can test for pertussis, not chiropractors and homeopaths. Parents who followed Meryl's advice would not be registered as pertussis cases for this study. Which means there's a very strong reason to believe that the pertussis rates in unvaccinated children are higher than reported, and they're even worse off.

    Bad luck Meryl, if even the few who go to ebil doctors are showing more disease, it must be terrible for the poor kids who aren't even being treated.

    ReplyDelete
  9. Ha ha, Meryl is funny!

    http://meryldorey.org

    ReplyDelete
  10. ...use of this vaccine is not only useless at preventing the occurrence of pertussis, but may be responsible for the emergence of more virulent strains of pertussis bacteria... [Meryl]

    Really Meryl? Seriously? This is your idea of science?

    Let's say, for example, that my neighbourhood is plagued by black cats. They outnumber white cats by 1000:1. Now, if I shoot all the black cats, the white cats will eventually dominate and we'll have a problem with white cats instead. But if I shoot the black cats with blanks then the white cats will remain a tiny minority because the black cats won't be affected.

    So, if the vaccine is useless against pertussis (like shooting cats with blanks), how does it cause it to evolve?

    ReplyDelete
  11. The pertussis vaccine is not working. [Meryl]

    Meryl draws this conclusion on the basis that some vaccinated people still get pertussis.

    Interestingly, she does not draw the same conclusion about Vitamin C and homeopathy despite the FACT her own dog suffered and died after she used these treatments for snake bite.

    Her Nirvana fallacies are reserved only for mainstream treatments.

    ReplyDelete

You need a Google, LiveJournal, WordPress, TypePad, AIM or OpenID account to comment. If you need one of those, click on the appropriate link. Spam comments will be deleted. Comments on posts older than 30 days will go into moderation, due to the activities of commercial spammers.