Tag: HHE

Pertussis Outbreaks

Like measles and mumps, pertussis, or whooping cough, is another vaccine-preventable disease that has been increasing in recent years.

Pre-Vaccine Era Pertussis Outbreaks

Pertussis has been known since at least the Middle Ages, although the bacteria that causes pertussis, Bordetella pertussis, wasn’t discovered until 1906.

Like measles, pertussis was a top killer of young children in the pre-vaccine era.
Like measles, pertussis was a top killer of young children in the pre-vaccine era.

That discovery led to the later development of the first pertussis vaccines, but before then, pertussis was a big killer, with epidemic cycles every 2 to 5 years.

During one of these cycles in the United States, from 1926 to 1930, there were:

  • 909,705 cases, and
  • 36,013 deaths

Unfortunately, even natural infection doesn’t provide life-long immunity, so adults would get pertussis and give it to susceptible kids, who were most likely to die during these epidemics.

But even in non-epidemic years, a lot of folks got pertussis. The number of reported cases ranged from “just” 161,799 in 1928 to 202,210 in 1926. And during one of the biggest years, 1934, there were 265,269 cases!

Post-Vaccine Era Pertussis Outbreaks

That changed in the vaccine era.

The first pertussis vaccines were developed in the 1930s and became more widely used in the 1940s when it was combined into the whole-cell DTP vaccine.

This was replaced with the acellular DTaP vaccine in 1997, with the Tdap vaccine being added to the vaccine schedule in 2006.

These vaccines helped to greatly reduce how many people got pertussis and how many people died from pertussis:

  • 1940 – 183,866 cases
  • 1950 – 120,718 cases and 1, 118 deaths
  • 1960 – 14,809 cases and 118 deaths
  • 1970 – 4,249 cases and 12 deaths
  • 1980 – 1,730 cases and 11 deaths
  • 1990 – 4,570 cases and 12 deaths
  • 2000 – 7,867 cases and 12 deaths
  • 2010 – 27,550 cases and 26 deaths

They never eradicated pertussis though, and as you can see, recently, pertussis cases have started to rise again.

Is it a coincidence that whooping cough came back as more folks began to skip and delay vaccines for their kids?
Is it a coincidence that whooping cough came back as more folks began to skip and delay vaccines for their kids?

In 2012, there were 48,277 cases of pertussis in the United States, the most since 1950, when we had 68,687 cases. Unfortunately, with the rise in cases, we are also seeing the tragic consequences of this disease – 20 deaths in 2012, mostly infants under age 3 months.

Pertussis cases remained steady, but high, in 2013 and 2014, at around 30,000 cases in the United States.

In California, pertussis reached epidemic levels. The California Department of Public Health reported at least 11,114 cases in 2014 – the highest numbers of pertussis cases in the state in 70 years!

And as expected with the rise in cases, there were 3 pertussis related deaths in California that year – all infants who had contracted pertussis when they were less than 8 weeks old. Two of the infants became sick in 2013, but the third, a 5-week-old baby, got infected in 2014.

Another baby, only 25 days old died in early 2015, but will be counted as the 2nd death of 2014 since that is when the illness started. About 383 patients, mostly infants who are less than 4 months old, were hospitalized in California that year, including 80 who required intensive care. And according to the California Department of Public Health, about 82% of the cases in infants were born to mothers who did not receive a dose of Tdap during their third trimester of pregnancy.

What’s happened since then?

Pertussis cases are continuing to fall each year! In fact, with about 16,000 cases in the United States, 2017 may have ended with the lowest number of pertussis cases since 2008.

Still, with just 1,830 pertussis cases in California in 2016, there were two deaths – both infants who were younger than 3 months of age when they got sick. And there was at least one death in 2017, with similar rates of disease, although reports are still preliminary.

Why So Many Pertussis Outbreaks?

Ever since a 2010 California pertussis outbreak, in which there were 9,154 cases of pertussis, the most in 63 years, and 10 infants died, many people, especially parents, began wondering why we were seeing more pertussis these days.

Is it because the pertussis vaccines simply don’t work, as the anti-vaccine movement would have you think?

Or is it because there are higher rates of unvaccinated kids these days and parents using alternative immunization schedules, instead of the standard immunization schedule from the CDC?

James Cherry, MD is an expert on pertussis and pertussis vaccines.
James Cherry, MD is an expert on pertussis and pertussis vaccines.

A commentary, Why Do Pertussis Vaccines Fail?, by James Cherry, MD, gave us some answers.

While the title of the article might have you think that all of the blame lies with the pertussis vaccines, that certainly isn’t the case. While there can be vaccine failures with the pertussis vaccines, just like any other vaccine, that doesn’t mean that the vaccine doesn’t work for most children.

One of the problems is that the DTaP vaccine likely isn’t as effective as the older DTP vaccine. So instead of efficacy of 84 to 85%, as was once believed, it is likely closer to just 71 to 78%.

Other issues, including waning immunity, the possibility of an incorrect balance of antigens in the vaccine that could create a blocking effect, and genetic changes in the B. pertussis bacteria, could also possibly lead to increased vaccine failure rates.

So it isn’t that the pertussis vaccines don’t work.

That should be easy to see when you look at the pertussis rates in California, when the highest rates by far were in infants less than 6 months of age (434 per 100,000 people). In contrast, children who were 6 months to 6 years old had a rate of only 62 per 100,000.

And the results of a study that were presented at the 49th annual meeting of the Infectious Diseases Society of America in Boston show just how important the pertussis vaccine is, as:

  • vaccine effectiveness was 98.1 percent among children who received their 5th dose within the past year
  • long term effectiveness – children who were five or more years past their last DTaP dose – was about 71 percent
  • children who had never received any doses of DTaP (unvaccinated children) faced odds of having whooping cough at least eight times higher than children who received all five doses

It is also important to note that the high rates seen in 2010 in California are still well below the rates that were seen in the pre-vaccination era, when the attack rate of pertussis in the United States was as high as 157 per 100,000 people, with about 200,000 cases a year.

What’s the answer?

“The present “resurgence of pertussis” is mainly due to greater awareness and the use of PCR for diagnosis. There are also many other factors which have contributed to the “resurgence.” New vaccines are clearly needed; with our present vaccines (DTaP and adolescent and adult formulated tetanus and diphtheria toxoids and acellular pertussis vaccine (Tdap)), if used correctly, severe pertussis and deaths in infants can be prevented.”

James D. Cherry, MD on The History of Pertussis (Whooping Cough); 1906 – 2015: Facts, Myths, and Misconceptions

It certainly isn’t for more kids to follow non-standard, parent-selected, delayed protection vaccine schedules or to simply skip vaccines all together. Since natural immunity isn’t going to keep newborns and infants from getting pertussis, the ages which are most at risk for life-threatening infections, they can catch pertussis from people around them, including those working on their natural immunity. Natural infections don’t even provide life-long protection against pertussis, as some people believe. That natural immunity wanes fairly quickly too.

Not Vaccinated? No Kisses!
Not Vaccinated? No Kisses!

The future of pertussis control is more likely going to be in maximizing our current vaccination program, including getting more teens and adults to get the Tdap vaccine, especially when women are pregnant.

That’s the best strategy, at least until new pertussis vaccines are developed. It provides a lot of benefits. According to the CDC, like with the flu vaccine, when you get a pertussis vaccine, in addition to protecting yourself and those people around you, “people who do catch whooping cough after being vaccinated are much less likely to be hospitalized or die from the disease.”

Unfortunately, not everyone has gotten the message. And because of waning immunity, children who aren’t vaccinated against pertussis can’t “hide in the herd” and rely on the rest of us who do vaccinate our children to provide them with protection. Instead, since they are at a higher risk, they get pertussis and get even more people sick.

This slogan, during a whooping cough epidemic, reminded parents to get their kids vaccinated now.
This slogan, during a whooping cough epidemic, reminded parents to get their kids vaccinated now.

In one study, Parental refusal of pertussis vaccination is associated with an increased risk of pertussis infection in children, researchers found that “vaccine refusers had a 23-fold increased risk for pertussis when compared with vaccine acceptors, and 11% of pertussis cases in the entire study population were attributed to vaccine refusal.” The highly contagious nature of pertussis then means every primary case is probably going to infect as many as 17 other people. That’s why it makes sense that higher rates of children using vaccine exemptions could be at least one of the factors in these outbreaks.

In fact, several studies, including, Geographic Clustering of Nonmedical Exemptions to School Immunization Requirements and Associations With Geographic Clustering of Pertussis, found that “geographic pockets of vaccine refusal are associated with the risk of pertussis outbreaks in the whole community.”

Get educated. Vaccines are safe and as you can see with the rise in outbreaks, vaccines are necessary.

What to Know About Pertussis Outbreaks

Many factors are responsible for the rise in pertussis outbreaks in recent years, but it is clear that being unvaccinated and unprotected put you at greatest risk for getting pertussis and passing it on to others.

More on Pertussis Outbreaks

Precautions vs Contraindications When Vaccinating Your Kids

Believe it or not, there are some anti-vaccine folks who believe that all vaccines are dangerous and unnecessary. And they believe that pediatricians push vaccines on kids in all situations, using a one-size-fits-all kind of immunization schedule.

Of course, neither is true.

Vaccines are safe and necessary.

There are some true medical contraindications and precautions to getting vaccinated though. Still, it is important to remember that even more things are simply “conditions incorrectly perceived as contraindications to vaccination.”

Contraindications To Vaccinating Your Kids

There are actually some good reasons to delay or skip one or a few of your child’s vaccines, but only in some very specific situations.

These very specific situations are called contraindications and are what count as medical exemptions.

“A vaccine should not be administered when a contraindication is present; for example, MMR vaccine should not be administered to severely immunocompromised persons.”

CDC on Vaccine Contraindications and Precautions

Fortunately, there are not that many of these contraindications, they are usually specific to just one or a few vaccines, and they are usually, but not always, temporary.

That’s why it would be really unusual to get a true permanent medical exemption for all vaccines. Even if you had a severe allergy to a vaccine that contained yeast, latex, or gelatin, since vaccines contain different ingredients, you would very likely be able to safely get the others.

Remember, your doctor can’t, or at least shouldn’t, just make up contraindications and exemptions to help you avoid getting your kids vaccinated and help you keep them in school.

“I do not believe vaccines had anything to do with my child’s autism. I never noticed any change in his speech, behavior or development with vaccines. I believe the protection and benefits of vaccines far outweigh the risks!”

Michele Han, MD, FAAP

Autism, for example, has been shown to not be associated with vaccines, so it is not a contraindication to getting vaccinated. That’s why many parents vaccinate and protect their autistic kids!

Precautions To Vaccinating Your Kids

In addition to contraindications to getting vaccinated, there is an accompanying list of  precautions.

“A precaution is a condition in a recipient that might increase the risk for a serious adverse reaction, might cause diagnostic confusion, or might compromise the ability of the vaccine to produce immunity (e.g., administering measles vaccine to a person with passive immunity to measles from a blood transfusion administered up to 7 months prior). A person might experience a more severe reaction to the vaccine than would have otherwise been expected; however, the risk for this happening is less than the risk expected with a contraindication. In general, vaccinations should be deferred when a precaution is present. However, a vaccination might be indicated in the presence of a precaution if the benefit of protection from the vaccine outweighs the risk for an adverse reaction.”

CDC on Vaccine Contraindications and Precautions

Again, we are fortunate that most of the conditions that are listed as precautions are temporary.

The vaccine information sheet that you get with each vaccine will list contraindications and precautions on who should not get the vaccine.
The vaccine information sheet that you get with each vaccine will list contraindications and precautions on who should not get the vaccine.

In fact, the most common is having a “moderate or severe acute illness with or without fever.”

Don’t want to get your child vaccinated when he or she has a severe illness?

Don’t worry.

Your pediatrician usually doesn’t want to vaccinate your child in that situation either.

It is easy enough to wait a few days or a week to get vaccinated, when the illness has passed, keeping in mind that a “mild acute illness with or without fever” is neither a precaution nor a contraindication to getting vaccinated. So you can still get your child their recommended vaccines if they just have a cold, stomach bug, or ear infection, etc.

What to Know About Precautions and Contraindications to Vaccines

Although there are some true medical exemptions or contraindications and precautions to getting vaccinated, most are vaccine specific and many are temporary, so they shouldn’t keep you from getting your child at least mostly vaccinated and protected.

More on Precautions and Contraindications to Vaccines

What Are Hypotonic-Hyporesponsive Episodes?

Just about any side effect after a vaccine can be scary for parents.

What if your child suddenly became limp, wasn’t responsive, and was pale?

That would be scary for any parent.

What Are Hypotonic-Hyporesponsive Episodes?

But that’s just what can happen when a child has a hypotonic–hyporesponsive episode (HHE).

“A hypotonic-hyporesponsive episode (HHE) is the sudden onset of hypotonia, hyporesponsiveness, and pallor or cyanosis that occurs within 48 hours after childhood immunizations.”

DuVernoy et al on Hypotonic-hyporesponsive episodes reported to the Vaccine Adverse Event Reporting System (VAERS), 1996-1998

These types of episodes were once thought to happen once for every 1,750 DTP vaccines given.

HHE is much more rare since we switched to a new pertussis vaccine.
HHE is much rarer since we switched to a new pertussis vaccine.

Fortunately, although they certainly do sound scary, the episodes stop on their own and  don’t cause any permanent harm.

Hypotonic-hyporesponsive episodes were even removed as table injuries after DTP back in 1995. It is not that HHE can’t occur after DTP, DTaP, or other vaccines, but rather that HHE doesn’t then cause any permanent neurological damage to the child.

And it is rare for kids to have a second episode, so they can continue to get vaccinated. HHE is not a good reason to skip or delay all of your child’s vaccines. While not a contraindication to getting vaccinated, having an episode of HHE “within 48 hours after receiving a previous dose of DTP/DTaP,” is listed as a precaution to getting another dose of DTaP or Tdap though.

“In general, vaccinations should be deferred when a precaution is present. However, a vaccination might be indicated in the presence of a precaution if the benefit of protection from the vaccine outweighs the risk for an adverse reaction.”

CDC on Vaccine Contraindications and Precautions

Also, HHE has become even more rare since we switched to using DTaP, instead of the older DTP vaccine. So being worried about HHE is definitely not a good reason to skip or delay any vaccines.

What to Know About Hypotonic-Hyporesponsive Episodes

Hypotonic-hyporesponsive episodes were more common after the older DTP vaccines, but still didn’t cause any long term problems and aren’t a good reason to skip or delay your child’s vaccines.

More About Hypotonic-Hyporesponsive Episodes