Tag: epitope

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?

Is the Polio Vaccine Linked to Outbreaks of Hand Foot Mouth Disease?

Wait, why would anyone think that the polio vaccine could be linked to outbreaks of hand, foot, and mouth disease?

“Scientific researchers have discovered that the infectious disease Hand,Foot and Mouth Disease is vaccine-induced and then spread to others through shedding from the Polio Vaccine. Enterovirus 71 (EV71) causes Hand, Foot, and Mouth Disease. The polio vaccine (OPV and IPV) is contaminated with EV71. It, along with EV-D68 and several other enteroviruses and coxsackie viruses are used in the manufacturing of the polio vaccines, which are given to children three times in the first year of life, and again between 4-6 years of life. Bottom line: children recently vaccinated with the polio vaccine are shedding the EV71 that causes the most serious complications of HFMD. ”

Health Freedom Idaho

Shedding

Is the Polio Vaccine Linked to Outbreaks of Hand Foot Mouth Disease?

Health Freedom Idaho makes some very serious claims and even links to a research article, which in most cases, you would expect to support their claims.

Not surprisingly, the article, A Dominant EV71-Specific CD4+ T Cell Epitope Is Highly Conserved among Human Enteroviruses, says absolutely nothing about contamination of vaccines and nothing about shedding.

“Recognizing disingenuous claims made by the anti-vaccination movement is essential in order to critically evaluate the information and misinformation encountered online.”

Anna Kata Anti-vaccine activists, Web 2.0, and the postmodern paradigm – An overview of tactics and tropes used online by the anti-vaccination movement

What about a link between polio vaccines and hand, foot, and mouth disease?

It is sad that anti-vaccine propaganda gets shared so quickly among parenting groups.
It is sad that anti-vaccine propaganda gets shared so quickly among some parenting groups, who’s members obviously don’t read the articles when they do their research.

Well, hand, foot, and mouth disease is typically caused by the coxsackievirus A16 and EV71, which are enteroviruses. So is the polio virus. In fact, the Enterovirus genus is made up of 15 different species and 100s of different viruses. And they are all in the same Picornavirus family.

And that’s likely why researchers have found that “the most dominant epitope is highly conserved among enterovirus species, including HFMD-related coxsackieviruses, HFMD-unrelated echoviruses and polioviruses.”

Epitope?

“An epitope refers to the specific target against which an individual antibody binds.”

What is an Epitope?

So basically, this research isn’t saying that the polio vaccines are contaminated or that they cause hand, foot, mouth disease.

What it is saying, is that if you have been vaccinated with the polio vaccine, then you might have some protection against other enteroviruses!

“As shown here, poliovirus vaccination may have an impact on subsequent severity of HFMD disease. Cross-reactivity between EV71 A3 epitope and the A3v epitope of poliovirus 3 Sabin strain, may lead to the stimulation of protective, cross-reactive T cell responses, limiting the severity of subsequent HFMD.”

Wei et al. on A Dominant EV71-Specific CD4+ T Cell Epitope Is Highly Conserved among Human Enteroviruses

Yay for cross-reactivity!

“Cross-reactivity between antigens occurs when an antibody directed against one specific antigen is successful in binding with another, different antigen. The two antigens in question have similar three-dimensional structural regions, known as epitopes, which allow the antibody for one antigen to recognize a second antigen as being structurally the same antigen.”

Stephen J. Chadwick, MD

So you get antibodies from the polio vaccine and these antibodies cross react with the viruses that cause hand, foot, and mouth disease, which could lead to milder symptoms, because it is like you already have some antibodies to that virus too!

“HFMD outbreaks could occur where polio vaccination has failed, due to lack of refrigeration or other breaks in the cold chain that (might) go unreported.”

Exploring the Link between Polio Vaccination and Hand Foot Mouth Disease

In China, where outbreaks of hand, foot, and mouth disease are much more severe than they are in the United States, often leading to life-threatening disease, there has been a concern that the increased number of outbreaks could be linked to a failure of their polio vaccines, since getting vaccinated could be protective.

That’s the link the research is talking about…

I actually asked one of the researchers about what anti-vaccine folks were saying about their study and they told me:

“Well, that’s actually totally backwards. Our article suggests that FAILURE to get vaccinated with polio vaccine might set you up for Hand Food Mouth disease (EV71).”

Bottom line: polio vaccines are not contaminated and children recently vaccinated with the polio vaccine are not shedding the EV71 that causes the most serious complications of HFMD. Health Freedom Idaho made the whole thing up.

More on Linking the Polio Vaccine to Hand Foot Mouth Disease