Tag: DPT

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

Antigen Counts in Vaccines

Vaccines contain antigens from toxins, viruses, or bacteria that help your body produce antibodies to help prevent future infections.

Of course, we are all exposed to these types of antigens every day.

In fact, experts state that we are exposed to thousands, if not millions, of antigens each day.

Eating. Drinking. Breathing. Touching things. These every day actions all can introduce antigens from viruses, bacteria, parasites, and toxins, etc., into our bodies.

And even though kids get many more vaccines today, and are protected against many more vaccine-preventable diseases than they once were, they actually get far fewer antigens from those vaccines than they once did.

Newer vaccines have a fraction of the antigens that the older DPT and smallpox vaccines once did.

That’s why the popular “too many too soon” anti-vaccine myth shouldn’t scare you from getting your kids vaccinated and protected.

Vaccine Antigen Counts

If you are still stuck on the actual number of vaccines, it is important to “understand that the numbers of antigens given are actually much less than they used to be. This is because we are giving purer vaccines. Vaccines have been isolated down to just the proteins needed to produce protection.”

The antigens are the things in the vaccines that actually trigger the production of antibodies and include antibody-stimulating proteins and polysaccharides.

In 1960, kids got up to 3,217 different antigens from the smallpox, polio, diphtheria, tetanus and whole cell pertussis vaccine.

In 1980, even as MMR replaced the smallpox vaccine, the antigen count in the vaccines kids got was still up to 3,041.

Kids Today Get Purer Vaccines

Even with many more vaccines, the number of different antigens that children will get with today’s immunization schedule is much lower than just 35 or 55 years ago:

  • DTaP/Tdap – 7 antigens
  • MMR – 24 antigens
  • IPV – 15 antigens
  • Hib – 2 antigens
  • Varicella – 69 antigens
  • Prevnar13 – 14 antigens
  • hepatitis A – 4 antigens
  • hepatitis B – 1 antigens
  • MCV4 – 5 antigens
  • HPV9 – 9 antigens
  • rotavirus – 15 antigens
  • Flu – 12 antigens

That’s just 177 different antigens in 12 vaccines that protect children against 16 vaccine-preventable diseases.

That’s still less than the 200 antigens that were in the smallpox vaccine that kids got 100 years ago.

Even considering that kids get multiple doses of many of these vaccines, with today’s complete vaccine schedule, from birth to age 18, including yearly flu shots, they would get a combined total of just 653 antigens. That’s still much less than a single dose of the DTP vaccine that kids got until 1997, when it was replaced by the DTaP vaccine.

With the 1980 immunization schedule, kids got 5 doses of DTP, 4 doses of OPV, a dose of MMR, and a dose of Td, combining to a grand total of at least 15,096 antigens.

Immune System Response to These Antigens

Of course, this is not to say that kids were exposed to too many antigens in vaccines in the past.

“Current studies do not support the hypothesis that multiple vaccines overwhelm, weaken, or “use up” the immune system. On the contrary, young infants have an enormous capacity to respond to multiple vaccines, as well as to the many other challenges present in the environment. ”

Offit et al on Addressing Parents’ Concerns: Do Multiple Vaccines Overwhelm or Weaken the Infant’s Immune System?

Looking at the antigen load of vaccines is simply another way to understand that kids don’t get too many vaccines too soon.

In fact, they get exposed to many more antigens from natural infections. A strep throat infection, for example, exposes kids to at least 25 to 50 antigens. That’s comparable to the antigens in the vaccines that infants get at their two month visit – the DTaP, IPV, HepB, Hib, and rotavirus vaccines combine to just 54 antigens.

But it is not just infections that lead to antigen exposures. Kids are exposed to 2,000 to 6,000 antigens every day and the “vaccines that children receive in the first two years of life are just a drop in the ocean when compared to the tens of thousands of environmental challenges that babies successfully manage every day.”

What to Know About Antigen Counts in Vaccines

Although kids get more vaccines today that their parents and grandparents, they get far fewer antigens from those vaccines.

More About Antigen Counts in Vaccines