Tag: pertussis outbreaks

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

What Happened When Sweden Stop Using the DPT Vaccine?

Do you ever wonder what would happen if we stopped vaccinating our kids?

You don’t have to wonder.

What Happened When Sweden Stop Using the DPT Vaccine?

It’s been done…

Remember when Sweden stopped using the DPT vaccine?

Endemic pertussis returned when they stopped using the DPT vaccine in Sweden.
Endemic pertussis returned when they stopped using the DPT vaccine in Sweden.

Between 1979 and 1996, Sweden suspended vaccination against pertussis because of concerns about the DPT vaccine.

Justus Ström's data was wrong...
Justus Ström‘s data was wrong…

And what happened?

“In 1979, the Swedish medical society abandoned whole-cell pertussis vaccine and decided to wait for a new, safer, more effective vaccine – a strategy that was soon adopted as national policy. During 1980-83, annual incidence for children aged 0–4 years increased to 3370 per 100000, with rates of serious complications approaching global rates. In subsequent years, Sweden reported more than 10000 cases annually with an incidence exceeding 100 per 100000, comparable to rates reported in some developing countries.”

Ganarosa et al on Impact of anti-vaccine movements on pertussis control: the untold story.

Pertussis came back.

In fact, endemic pertussis came back.

“Our evaluation of pertussis in the unimmunized child population gave an answer to the question of whether pertussis nowadays is a harmless disease which does not demand general vaccination. The present situation regarding pertussis in Sweden and the low efficacy of the antimicrobial treatment indicate an urgent need to prevent the disease by general vaccination as soon as a safe and effective vaccine is available.”

Romanus et al on Pertussis in Sweden after the cessation of general immunization in 1979.

Of course, they already had a safe and effective vaccine at the time.

All of the claims against the whole cell pertussis vaccine ended up being untrue.

The incidence of SIDS didn't drop when they stopped using the DPT vaccine in Sweden.
The incidence of SIDS didn’t drop when they stopped using the DPT vaccine in Sweden.

Not surprisingly, even though they weren’t using the DPT vaccine, rates of SIDS didn’t drop until they implemented the back to sleep recommendations.

If vaccines are associated with SIDS, shouldn’t the incidence of SIDS have decreased when they stopped giving infants the DPT vaccine?

More on What Happens If We Stop Vaccinating

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?

Why Are We Worried About 60,000 Unvaccinated Kids?

In the recent New York Times OpEd, How to Inoculate Against Anti-Vaxxers, the editorial board mentioned the 60,000 children in Texas who “remain wholly unvaccinated thanks in part to an aggressive anti-vaccine lobby.”

“But there’s like 74 million children, so I think that’s a pretty small number. I don’t know why you guys are freaking out about 60,000 really healthy babies running around. Do you know?

Hillary Simpson

Hillary Simpson obviously doesn’t understand how herd immunity works.

Do you?

Why Are We Worried About 60,000 Unvaccinated Kids?

First things first, though.

Just how many unvaccinated kids are there in Texas? How about the United States?

It is actually hard to know exactly.

It's easy to forget, with so much talk about anti-vaxxers these days, but the great majority of parents vaccinate and protect their kids!
It’s easy to forget, with so much talk about anti-vaxxers these days, but the great majority of parents vaccinate and protect their kids!

In Texas, for instance, while only a small percentage of kids get non-medical vaccine exemptions, with about 7 million children in the state (yes, there are 74 million children in the United States, but that’s not how you measure herd immunity), that adds up to a lot of unvaccinated kids.

In addition to about 60,000 unvaccinated kids in school, there are homeschooled children who aren’t vaccinated.

“We’re probably looking at more than 100,000 kids in the state of Texas who are not getting their vaccines.”

Dr. Peter J. Hotez: “A Scary Anti-Science Movement Has Become Very Strong in Texas”

But still, should we be worried about 100,000 unvaccinated kids, when there are 7 million kids in Texas?

Don’t those immunization levels still keep us above herd immunity levels of protection?

Well, they likely would, and this would indeed be less concerning if the unvaccinated children were spread out randomly throughout the entire state. Of course, that’s not what happens and we instead get clusters of unvaccinated children (and adults) in very specific schools, neighborhoods, and even churches.

There are higher numbers of unvaccinated kids in very specific parts of the states, leading to pockets where it is more likely that an outbreak could happen.
There are higher numbers of unvaccinated kids in very specific parts of the states, leading to pockets where it is more likely that an outbreak could happen.

So while it can seem like we have herd immunity levels of protection at the state or city level because of high average vaccination levels, these pockets of susceptibles who are unvaccinated and live in the same neighborhood or go to the same school (where is the Waldorf school in Texas?) can mean that we don’t have herd immunity in those places, leading to outbreaks.

And that’s why we get concerned about 60 to 100,000 unvaccinated children who:

Still, remember that the great majority of parents understand the benefits of vaccines, are not scared by anti-vaccine propaganda, and vaccinate their kids.

In 2015, for example, only 1.3% of children in the United States had received no vaccines by age 24 months. And more than 90% of children completed their primary series of vaccines.

That doesn’t mean that we shouldn’t be concerned about those who don’t, but maybe you should be a little bit more concerned about your decision to not vaccinate your kids.

More on Clusters of Unvaccinated Kids

Vaccine-Preventable Diseases – Year in Review 2018

Does it seem like we are moving in the wrong direction?

The eradication of smallpox shows just what vaccines can do!
The eradication of smallpox shows just what vaccines can do!

No, smallpox isn’t coming back, but many other vaccine-preventable diseases are.

Vaccine-Preventable Diseases – Year in Review 2018

With the availability of new vaccines and the expanded use of other vaccines, many of us were hopeful of the progress that was being made against vaccine-preventable diseases so far this decade.

Remember, it was just four years ago that the WHO certified India as a polio free country. And after years of declining numbers of wild polio cases, 2018 will be the first year with a higher number of cases than the previous year.

This hasn’t been a good year for measles either. The WHO Region of the Americas has lost its status as having eliminated measles!

In Bolivarian Republic of Venezuela, endemic transmission of measles has been re-established, with spread to neighbouring countries. As a result, the Region has lost its status as having eliminated measles. The Regional Technical Advisory Group, which met in July 2018, emphasized the importance of Regional action and an urgent public health response to ensure re-verification of measles elimination in Bolivarian Republic of Venezuela.

Meeting of the Strategic Advisory Group of Experts on Immunization, October 2018 – Conclusions and recommendations

After years of declining rates, global measles cases and deaths began to jump in 2017, a trend that continued in 2018.

“Outbreaks in North America and in Europe emphasize that measles can easily spread even in countries with mature health systems. Due to ongoing outbreaks, measles is again considered endemic in Germany and Russia.”

2018 Assessment Report of the Global Vaccine Action Plan

And no, this isn’t just a problem in other parts of the world.

Vaccine preventable diseases are just a plane ride away.
Vaccine preventable diseases are just a plane ride away.

More cases in other parts of the world mean more cases in the United States because unvaccinated folks travel out of the country and bring these diseases home with them, getting others sick.

But it wasn’t just measles outbreaks, including the second largest number of cases in 22 years, that we were seeing in 2018:

  • chicken pox – although the 41 cases involving a North Carolina Waldorf school got the most attention, there were at least 6,892 cases of chicken pox last year, which continues to trend down from recent highs of over 15,000 in 2010
  • hepatitis A – clusters of outbreaks in 15 states with at least 11,166 cases, many deaths, with exposures at popular restaurants
  • mumps – from recent highs of over 6,000 cases the last few years, we were “back down” to just over 2,000 mumps cases in 2018
  • pertussis – cases were also down in 2018, with a preliminary count of about 13,439 cases last year
  • meningococcal disease – isolated outbreaks continued last year, with cases at Smith College, Colgate University, and San Diego State University

And of course, we had one of the worst flu seasons in some time last year, with 185 pediatric flu deaths.

Fortunately, there were no cases of diphtheria, neonatal tetanus, polio, or congenital rubella syndrome. At least not in the United States.

Why are some disease counts down when so many folks say the anti-vaccine movement is more active than ever?

Remember, the great majority of people vaccinate and protect their kids!

And vaccines work!

It is best to think of the anti-vaccine movement, which has always been around, as a very vocal minority that is just pushing propaganda to scare parents away from vaccinating and protecting their kids.

As more people are vaccinated and diseases disappear, they forget how bad those diseases are, skip or delay getting their vaccines, and trigger outbreaks.
As more people are vaccinated and diseases disappear, they forget how bad these diseases are, allow themselves to be influenced by anti-vaccine propaganda, skip or delay getting their vaccines, and trigger outbreaks. Photo by WHO

Also remember that many of these diseases occurred in multi-year cycles in the pre-vaccine era. When an up year hits a cluster of unvaccinated kids, we get bigger outbreaks. And then more folks get vaccinated, starting the cycle all over again. At least until we finally get the disease under better control or finally eradicated.

Want to avoid getting a vaccine-preventable disease this year?

Get vaccinated and protected and encourage everyone else to get vaccinated too.

More on Vaccine-Preventable Diseases – Year in Review 2018

Do More Vaccinated or Unvaccinated Kids Get Pertussis?

While this seems like a simple question, the answer is a bit more complicated than most people imagine.

Do More Vaccinated or Unvaccinated Kids Get Pertussis?

For anti-vaccine folks, the answer is clear – more vaccinated kids get pertussis. They put all of the blame for pertussis outbreaks on waning immunity. Of course, that’s not the whole story.

While 10% of kids got pertussis, unless you are at a Waldorf school, it is unusual to find that many completely unvaccinated children.
While 10% of kids got pertussis, unless you are at a Waldorf school, it is unusual to find that many completely unvaccinated children. Plus, we don’t know the vaccine history of 40% of these kids.

While it might technically be true that more vaccinated kids get pertussis in the average outbreak, that’s only because there are many more vaccinated kids!

A more accurate and useful answer, taking into account attack rates, makes it clear that a higher percentage of unvaccinated kids get pertussis in these outbreaks.

“In conclusion we have described a school-based outbreak of pertussis that may have been fueled by moderate vaccine effectiveness combined with a failure to vaccinate.”

Terrenella et al on Vaccine effectiveness of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine during a pertussis outbreak in Maine

In a pertussis outbreak in Maine, attack rates were much higher in unvaccinated kids, even though more vaccinated kids got pertussis. While 29 of 214 vaccinated kids got pertussis, a much higher percentage of unvaccinated kids got sick – 6 of 28.

That means your risk of getting pertussis was much higher if you were unvaccinated.

A 2013 pertussis outbreak in Florida is a good example that even with all the bad press it gets, the DTaP and Tdap vaccines work too. This outbreak was started by an unvaccinated child at a charter school with high rates of unvaccinated kids. About 30% of unvaccinated kids got sick, while there was only one case “in a person who reported having received any vaccination against pertussis.”

In another 2013 pertussis outbreak in Florida, this time in a preschool, although most of the kids were vaccinated, the outbreak started with “a 1-year-old vaccine-exempt preschool student.” And the classroom with the highest attack rate, was “one in which a teacher with a laboratory-confirmed case of pertussis who had not received a Tdap booster vaccination, worked throughout her illness.”

Why do so many unvaccinated kids get pertussis these days?

“We found evidence of an increase in exemption rates, spatial clustering of nonmedical exemptions, and space-time clustering of pertussis in Michigan. There was considerable overlap between the clusters of exemptions and the clusters of pertussis cases.”

Omer et al on Geographic Clustering of Nonmedical Exemptions to School Immunization Requirements and Associations With Geographic Clustering of Pertussis

Besides the fact that they are unvaccinated and unprotected?

“Children of parents who refuse pertussis immunizations are at high risk for pertussis infection relative to vaccinated children. Herd immunity does not seem to completely protect unvaccinated children from pertussis.”

Glanz et al on Parental refusal of pertussis vaccination is associated with an increased risk of pertussis infection in children.

They can’t get away with hiding in the herd.

Another important consideration – in addition to the fact that more unvaccinated kids get pertussis, when they get pertussis, it is more severe than those who are vaccinated.

“Serious pertussis symptoms and complications are less common among age-appropriate number of pertussis vaccines (AAV) pertussis patients, demonstrating that the positive impact of pertussis vaccination extends beyond decreasing risk of disease.”

McNamara et al on Reduced Severity of Pertussis in Persons With Age-Appropriate Pertussis Vaccination-United States, 2010-2012.

Still thinking of skipping or delaying your child’s pertussis vaccine?

More on Do More Vaccinated or Unvaccinated Kids Get Pertussis?