Hi. My name is Paul Offit. I am talking to you today from the Vaccine Education Center at Children's Hospital of Philadelphia. Today I want to talk about a letter to the editor that was published in the February 7, 2013, issue of the New England Journal of Medicine. It was titled "Pertactin-Negative Variance of Bordetella pertussis in the United States."
Researchers in Philadelphia looked at 12 strains of B pertussis that had been isolated from children who were hospitalized with the disease. They found that 11 of the 12 strains did not contain a particular protein, pertactin, which is an adhesion molecule. That protein is a component of several vaccines, including both Tdap vaccines and 2 of the 3 DTaP vaccines.
This article raises the question of whether or not this is important. We certainly know that although these strains have been isolated in Japan, France, and Finland, there is no evidence that they are related to epidemics there. To date, the isolates that have been associated with outbreaks in the United States also contain pertactin. Thus, there is no evidence that these strains are anything other than a curiosity.
I would argue that they are a microbiological curiosity in search of clinical relevance. Unfortunately, the media has picked up this story and has implied that maybe we are creating these superstrains [of microbes] that are causing these outbreaks -- when, frankly, all of the evidence points to the notion that we have waning immunity because the acellular pertussis vaccine is just not as effective as our previous whole-cell vaccine was.
The current pertussis vaccine, although not as effective as the previous vaccine, is still the best tool we have. If you look at that recent California outbreak, patients who received the current acellular pertussis vaccine were 8-fold less likely to get pertussis than those who did not get that vaccine. We will see over time whether or not this finding is in any sense clinically relevant. I predict that that is will not be the case.
Thank you for your attention.
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Cite this: Pertactin and Vaccines: Important or Not? - Medscape - Mar 15, 2013.