Dr. Sears, this discussion comes up a lot on the vaccination forum, and I was wondering if you could share your insights.
Most of the posters who claim that DTaP does NOT prevent transmission of pertussis link to a page on this primarily anti-vax website. (Despite the cite's bias, the citation are compelling). Here is a similar page on the topic.
For your reference, here is a past MDC thread on the topic.
I would really appreciate it if you could share what you know on this issue. I do give my children this vaccine, largely because I don't want them spreading pertussis. Thanks in advance for your response.
This is what the vaccine manufacturer, Sanofi Pasteur, says about the Tdap vaccine.
"It is unknown whether immunizing adolescents and adults against pertussis will reduce the risk of transmission to infants."
I read about this debate over the years, and I'm still not sure what to think. The issue as to that "many or most people who get the disease are vaccinated" is not evidence that the vaccine doesn't prevent transmission, in my opinion. It just means that the vaccine doesn't always work. It IS one of the least effective vaccines there is. It's about 85 to 90% effective. That's why the disease isn't more common than it is - because the vaccine helps keep it at bay. I've heard that the vaccine can help prevent the disease from becoming severe and prolonged, but it doesn't actually stop the germ from infecting you. It just minimizes how severely the toxin affects you. That's why they say it doesn't prevent transmission. I don't know it that's true or not.
In my experience in the office, probably 90% of people who catch pertussis are not vaccinated. I do believe that in many people who get the vaccine, it works very well to prevent them from getting sick. I will admit that i haven't read everything there is on this issue. I don't have time right now to read through the links you've provided, but will put it on my list of issues to investigate.
Thank you, Dr. Sears, for agreeing to investigate the matter of transmission. I definitely believe in vaccinating babies against pertussis, despite the vaccine's apparent weakness. Yet the main reason that I would consider boosters for my older children (or myself!) would be for "herd immunity," and if there's not enough science to support the assumption that the vaccine prevents transmission, I may question going through with it.
While understanding that you are extremely pressed for time, I look forward to your response after you've reviewed some of the arguments surrounding this issue.
Thanks again for investigating,
Yes, thank you for responding, Dr. Sears. I too am very interested in this issue. Have an app't booked tomorrow for 4 yr old dd to have a booster (tet/dip/pertussis/polio). As we have a baby on the way this fall, I wanted her to have the extra protection from pertussis to reduce the risk of transmission to the babe (we had an outbreak in our region last year, mostly among the unvaccinated population) . I'm also curious about claims that the adult pertussis vaccine protects those around you. I don't believe this vaccine is available here in Canada (or perhaps it is if one purchases it privately...but public health doesn't offer it to the public). Given that many adult cases of pertussis seem to go unrecognized, I'm not sure how researchers would even begin to study the effectiveness of the adult vaccine.
(Btw, I thought the Vaccine Book was the most balanced and evidence-based of all the books on vaccines I read. Here in Canada, pediatricians and GP's recommend "Your Child's Best Shot" (Cdn Pediatric Society publication). The primary author happens to be a paid consultants to one of the vaccine manufacturers (and did disclose this). It paled in comparison to your book, which I think should be required reading for all physicians and public health nurses in Canada (and elsewhere)).