Tag: pertussis vaccines

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

About Those Lawsuits That Almost Put Vaccine Manufacturers out of Business

So you likely know that there were a bunch of lawsuits against manufacturers of the DPT vaccine in the early and mid 1980s.

“As the number of lawsuits grew to hundreds during the early 1980s, the pharmaceutical companies making vaccines saw their liability insurance bills soar. Worried not only about multimillion-dollar settlements, but also even the legal costs of defending themselves successfully, several companies simply stopped making vaccine.”

How a Media Scare On Vaccine Started a ‘near-Epidemic’

That’s why the National Vaccine Injury Compensation Act passed in 1986, creating the National Vaccine Injury Compensation Program and the Vaccine Court.

About Those Lawsuits That Almost Put Vaccine Manufacturers out of Business

But did those DPT vaccine lawsuits prove that vaccines aren’t safe?

Is that why vaccine manufacturers needed help to limit their liability?

“The total amount claimed in 1984 DTP vaccine suits ($1.3 billion) is more than 20 times the total value of 1984 sales of DTP vaccine at the market price of $2.80 per dose.”

Hinman on DTP Vaccine Litigation

Of course not!

While the older DPT vaccine did cause more local reactions, pain, and fever than the newer DTaP vaccine that replaced it, all of the serious reactions that triggered the lawsuits were later found to not be caused by the vaccine.

Most of the DPT lawsuits were thought to be frivolous.

That’s not surprising, as the same vaccine lawsuits that were succeeding in driving vaccine manufacturers out of business in the United States were failing in the UK and Canada!

This included the Loveday judgment in Great Britain’s High Court of Justice, Queen’s Bench Division and the Rothwell judgment in the Supreme Court of Ontario, Canada, both decided in 1988, with justices ruling that there was “insufficient evidence to demonstrate that pertussis vaccine can cause permanent brain damage in children.”

Similar cases were succeeding in the US though..

“The number (and dollar value) of suits increased in 1982, a year when broadcast and print media began to devote considerable attention to the alleged hazards associated with the use of pertussis-containing vaccines. Most of the media coverage has emphasized alleged risks of pertussis vaccines and has given relatively little attention to the benefits of their use.”

Hinman on DTP Vaccine Litigation

Most experts knew that most of the lawsuits were frivolous, but they weren’t able to stop the damage that was to come, as:

  • the DPT: Vaccine Roulette special aired on TV
  • Barbara Loe Fisher, believing that her child was damaged by the DPT vaccine, formed the Dissatisfied Parents Together organization and wrote the book DPT: A Shot in the Dark, which later influenced Bob Sears
  • there were temporary shortages of DTP vaccine in 1984, as “two of the three American manufacturers of the product decided to halt or restrict its sales.”

What else happened? I mean besides all of the studies proving the DPT vaccine was safe?

Parents who had been scared by the DPT controversy were ready and primed when Andy Wakefield showed up and told them that they had something new to worry about – the MMR vaccine and autism.

And of course, pertussis is now returning, as more parents are scared to vaccinate their kids and the newer DTaP vaccine isn’t as effective as DPT.

More on Those Lawsuits That Almost Put Vaccine Manufacturers out of Business

Are the Tdap and DTaP Vaccines the Same Thing?

You have probably already figured out the Tdap and DTaP aren’t the same vaccine, after all, if they were, why would they have different names, right?

Are the Tdap and DTaP Vaccines the Same Thing?

I bet you don’t know the difference between the two vaccines though.

Yes, they both are both combination vaccines that protect against diphtheria, tetanus, and pertussis.

The difference is that one (DTaP) is used as the primary series for infants and younger children (age 6 years and under) and the other (Tdap) is given to older children (age 7 years and above), teens, and adults.

Okay, that’s not the only difference.

The DTaP vaccine actually contains more diphtheria and pertussis antigens than Tdap, which is why it has the capital “D” and “P” in its name. The amount of tetanus toxoid antigens are about the same in both vaccines.

So Tdap contains the same amount of tetanus toxoid, plus a reduced amount of diphtheria and acellular pertussis antigens, as compared to DTaP.

While you would think that older children and adults would get the vaccine with the higher amount of antigens, since they are bigger, that’s not how this works. Vaccines typically start working at the injection site, so body size isn’t a key factor in determining the amount of ingredients.

As a booster dose of vaccine, the lower amount of antigens works just fine and helps reduce the risk of side effects from repeated doses that you might get with higher antigen counts.

More on Tdap vs DTaP

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?