Tag: James D. Cherry

Making a Better Pertussis Vaccine

So we know that we need a better pertussis vaccine.

DTaP and Tdap just aren’t doing the job that they should be doing.

Whooping Cough is back, again.
Whooping Cough is back, again.

So when will we get one?

Making a Better Pertussis Vaccine

Since anti-vaccine folks are always talking about the 300 new vaccines in the pipeline, you would think that we would have had several new pertussis vaccines by now…

Unfortunately, we don’t.

What we do have is some good candidates, including:

  • new acellular pertussis vaccines, either with more antigens or an adjuvant
  • a new live attenuated nasal vaccine, BPZE1
  • new whole-cell vaccines with reduced endotoxin contents (so should have fewer side effects that then original whole-cell pertussis vaccine – DTP)

Before you get too excited, keep in mind that none of these vaccines will be available in your pediatrician’s office any time soon. Developing a new vaccine takes a lot of time.

BPZE1 has started phase 2a trials though.

What do we do until we get new pertussis vaccines?

“We should be more vigilant than we have been in the past to recognize and treat pertussis in all age groups so that transmission to young infants is reduced. Most important (although not discussed in this review) is to ensure that all pregnant women receive the Tdap vaccine between 27 and 36 weeks’ gestation with each pregnancy. Also, we should consider routinely administering Tdap vaccine every 3 years to all adolescents and adults who were primed with a DTaP vaccine.”

James D. Cherry on The 112-Year Odyssey of Pertussis and Pertussis Vaccines—Mistakes Made and Implications for the Future

We should keep using the pertussis vaccines we have!

Vaccines work, even when they aren’t as effective as we would like.

More on Making a Better Pertussis Vaccine

Does Getting the DTaP Vaccine Make You More Susceptible to Pertussis?

Wait, why would anyone think that getting vaccinated would make you more likely to get a vaccine-preventable disease?

Because there is a new pertussis outbreak in California and folks don’t understand how attack rates work…

Does Getting the DTaP Vaccine Make You More Susceptible to Pertussis?

We know that the latest pertussis vaccines aren’t the greatest, having issues with waning immunity.

They don’t actually make you more likely to get pertussis though, at least not relative to being unvaccinated.

“Because of linked-epitope suppression, all children who were primed by DTaP vaccines will be more susceptible to pertussis throughout their lifetimes, and there is no easy way to decrease this increased lifetime susceptibility.”

JD Cherry on The 112-Year Odyssey of Pertussis and Pertussis Vaccines-Mistakes Made and Implications for the Future

What the above quote that anti-vaccine folks are misusing is actually saying is that kids who got DTaP vaccines will be more susceptible to pertussis compared to those who got DTwP, the older version of the vaccine. That’s what the whole article is about!

It is not that they will be more suspecptible to pertussis vs someone who was unvaccinated.

Dr. I: Anti-vax folks are misinterpreting that statement, not understanding that it means relative to kids who got DTwP. They think that you are saying that it is the DTaP vaccine itself that makes it more likely that a child will get pertussis, in general. Even relative to someone who is unvaccinated. I know it shouldn’t be necessary, but can you provide a simple quote to clarify this?

JDC: You are of course correct. I was asked to write-up the talk that I have given many times in the US and in many other countries. In the talk, right at the beginning, I mention that today there is 20 fold less pertussis than there was in the pre-vaccine era and that illness in vaccine failures is much less severe that illness in unvaccinated children. I also remember how wrong they were 30 years ago R/E alleged reactions to DTwP.

And if you read his latest article, The 112-Year Odyssey of Pertussis and Pertussis Vaccines-Mistakes Made and Implications for the Future, especially if you read more than the abstract, you discover that’s what he is saying.

But what about linked-epitope suppression?

In “linked-epitope suppression,” memory B cells out-compete naive B cells for access to the Bordetella epitopes because they are more numerous and their receptors exhibit a higher antigen affinity. Linked-epitope suppression applies as the immune response to novel epitopes is suppressed by the strong response to initial components if they are introduced together.

JD Cherry on The 112-Year Odyssey of Pertussis and Pertussis Vaccines-Mistakes Made and Implications for the Future

Basically, the DTwP vaccine included many more epitopes or targets for antibodies to bind to than the newer DTaP vaccine. That’s why it worked better. And you don’t get a good response to non-vaccine epitopes or antigens.

Still, you at least have some memory B cells and antibodies after getting the DTaP vaccine, which is why the idea that getting vaccinated makes you more susceptible to pertussis is silly. You are still protected, even if the protection isn’t perfect.

That’s why Dr. Cherry recommends that folks continue to get vaccinated and protected!

“We should be more vigilant than we have been in the past to recognize and treat pertussis in all age groups so that transmission to young infants is reduced. Most important (although not discussed in this review) is to ensure that all pregnant women receive the Tdap vaccine between 27 and 36 weeks’ gestation with each pregnancy. Also, we should consider routinely administering Tdap vaccine every 3 years to all adolescents and adults who were primed with a DTaP vaccine. This suggestion is contrary to that in the current Advisory Committee on Immunization Practices recommendations. However, from the data available, this approach could be expected to decrease the circulation of B pertussis in adolescents and adults. Also, Tdap should be administered to all adolescent and adults exposed to B pertussis during a school or other group outbreak.”

JD Cherry on The 112-Year Odyssey of Pertussis and Pertussis Vaccines-Mistakes Made and Implications for the Future

He does recommend that we work on new pertussis vaccines though.

“Future cohorts would benefit from the development and use of live vaccines and less-reactogenic DTwP vaccines.”

JD Cherry on The 112-Year Odyssey of Pertussis and Pertussis Vaccines-Mistakes Made and Implications for the Future

But why are we using a vaccine that doesn’t work as well as the previous vaccine we had?

“Despite the fact that in all but 2 of the efficacy trials the DTwP vaccines had greater efficacy than did the DTaP vaccines being studied, DTaP vaccines were licensed and used in many countries throughout the world; DTaP vaccines had replaced DTwP vaccines. The urgency to adopt DTaP vaccines was driven largely by antivaccine activist groups such as “Dissatisfied Parents Together.” During the rush to adopt DTaP vaccines and tetanus, diphtheria, acellular pertussis vaccines for adults (Tdap), much of the history relating to human pertussis was overlooked.”

JD Cherry on The 112-Year Odyssey of Pertussis and Pertussis Vaccines-Mistakes Made and Implications for the Future

But the DTwP vaccines weren’t safe, right?

“The results of a number of controlled studies between 1979 and 2004 indicated that no risk of severe neurologic disease after DTwP vaccinations existed. It was noted by myself and Shields (a pediatric neurologist) that what was being called pertussis vaccine encephalopathy was not an encephalitis-like event but, instead, the first seizure or seizures of infantile epilepsy.”

JD Cherry on The 112-Year Odyssey of Pertussis and Pertussis Vaccines-Mistakes Made and Implications for the Future

No, the cases of encephalopathy that were being reported were not caused by the DTwP vaccine. And neither did the DTwP vaccine cause SIDS, as was also reported at the time.

“Since 1997, the DTaP vaccination policy has created a cohort of people (the number of which is expanding yearly) who are more susceptible to repeated clinical illness with B pertussis infection than are DTwP-vaccinated children. There is no feasible way to make this cohort less susceptible.”

JD Cherry on The 112-Year Odyssey of Pertussis and Pertussis Vaccines-Mistakes Made and Implications for the Future

And now, after helping create the current DTaP vaccination policy, anti-vaccine folks want to scare folks away from using the vaccine. Don’t let them. Don’t skip or delay this vaccine and leave your kids susceptible to getting diphtheria, tetanus, and pertussis.

More on Does Getting the DTaP Vaccine Make You More Susceptible to Pertussis?