Tag: reporting vaccine side effects

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

Vaccines and the Risk of Intussusception

Many people first heard the term intussusception after it became associated with Rotashield, the first rotavirus vaccine, back in 1999.

What is Intussusception?

Intussusception is a type of intestinal blockage that occurs when one part of a child’s intestine in pulled into or slides into another.

This leads to younger children, typically between the ages of 3 months and 3 years, developing colicky abdominal pain (severe pain that comes and goes) and loose stools that are filled with blood and mucous.

Fortunately, if caught early, it can be both diagnosed and treated with an air contrast enema.

Do Rotavirus Vaccines Cause Intussusception?

Intussusception in children is not a new condition. In fact, Samuel Mitchel reported treating children with intussusception as early as 1838!

So what causes intussusception?

Surprisingly, in most cases, we just don’t know why kids get intussusception.

We do know that it occurs in about 1 in 100,000 US infants, with about 2,000 cases being diagnosed and treated each year.

“There is also a small risk of intussusception from rotavirus vaccination, usually within a week after the first or second dose. This additional risk is estimated to range from about 1 in 20,000 to 1 in 100,000 US infants who get rotavirus vaccine.”

CDC on Questions & Answers about Intussusception and Rotavirus Vaccine

And we know that getting a rotavirus vaccine adds a small extra risk for intussusception.

The association was found by looking at reports to VAERS and studies by the FDA’s Post-licensure Rapid Immunization Safety Monitoring System (PRISM).

And it is not just the original Rotashield vaccine, which was withdrawn, but the rotavirus vaccines that we now use that have also been linked to intussusception. The difference is that the risk is much less with the newer rotavirus vaccines.

“Given the magnitude of declines in rotavirus disease compared with this small increase in intussusception, the benefits of rotavirus vaccination outweigh the increase risk of intussusception.”

Tate et al on Intussusception Rates Before and After the Introduction of Rotavirus Vaccine

This small risk must also be viewed against the many benefits of the rotavirus vaccines.

“Rotavirus is the leading cause of severe gastroenteritis among young children worldwide, and was estimated to account for approximately one-third of the estimated 578,000 deaths from childhood gastroenteritis and more than 2 million hospitalizations and 25 million outpatient clinic visits among children <5 years of age each year in the pre-vaccine era.”

Parashar et al on Value of post-licensure data on benefits and risks of vaccination to inform vaccine policy: The example of rotavirus vaccines

Rotavirus vaccines are associated with a very small risk of intussusception, but that is not a good reason to miss the benefits of this vaccine.
Rotavirus vaccines are associated with a very small risk of intussusception, but that is not a good reason to miss the benefits of this vaccine. Photo by Vincent Iannelli, MD

It is also still not clear if the rotavirus vaccines actually “trigger” intussusception or if they simply cause it to occur earlier in infants that would have gotten it anyway. That’s because while the latest studies have found excess cases shortly after the first dose of vaccine, studies looking at intussusception trends “have not consistently demonstrated an overall increase in rates post-vaccination.” So there were the same number of total cases, even with the few extra cases right after the kids were vaccinated.

Also, it is thought that wild type rotavirus infections can also trigger intussusception, so the rotavirus vaccines might prevent those cases.

Most importantly though, remember that even if the rotavirus vaccines cause an extra 35 to 100 hospitalizations a year because of intussusception, they are preventing up to 70,000 hospitalizations from severe rotavirus diarrheal disease that occurred in the pre-vaccine era. The vaccines are also preventing about 20-60 deaths from rotavirus disease, while intussusception is rarely life-threatening.

If you are on the fence about vaccines, worry about intussusception is not a good reason to skip or delay your child’s vaccines.

What to Know About Vaccines and Intussusception

Because of a small risk of intussusception, parents should be aware of the symptoms and signs of intussusception and that they may appear six to eight days after an infant’s first dose of rotavirus vaccine.

More on Vaccines and Intussusception

Global Vaccine Side Effect Reporting Systems

Has your child had a bad reaction to a vaccine or what you think is a vaccine injury?

Did you or your pediatrician report it?

Reporting Side Effects to VAERS

The CDC advises that “all significant adverse events that occur after vaccination of adults and children, even if you are not sure whether the vaccine caused the adverse event.”

But VAERS isn’t for everyone.

VAERS is for anyone who gives or receives a licensed vaccine in the United States.

Global Vaccine Side Effect Reporting Systems

What to folks do outside the United States?

In Canada, Adverse Events following Immunization (AEFI) forms are submitted to the Canadian Adverse Events Following Immunization Surveillance System.
In Canada, Adverse Events following Immunization (AEFI) forms are submitted to the Canadian Adverse Events Following Immunization Surveillance System.

Not surprisingly, most countries have a reporting system for possible adverse events to vaccines that is similar to VAERS, including, but not limited to:

You can also report possible side effects directly to vaccine manufacturers.

And like our Vaccine Safety Datalink, in addition to having a passive reporting system, like VAERS, many countries have an active vaccine safety surveillance system to make sure that their vaccines are safe:

  • Australia – AusVaxSafety monitors 156 surveillance sites
  • Canada – IMPACT or Canada’s Immunization Monitoring Program ACTive that actively monitors “12 Canadian centres, which represent about 90% of all tertiary care pediatric beds in Canada” for “adverse events following immunization, vaccine failures and selected infectious diseases that are, or will be, vaccine preventable.”
  • UK – the Clinical Practice Research Datalink (CPRD)

A lot of this work is also done as part of the World Health Organization’s Global Vaccine Safety Initiative (GVSI). In fact, many (about 110) WHO member countries report to the VigiBase system that is actively monitored by the WHO’s Uppsala Monitoring Centre.

What to Know About Global Vaccine Side Effect Reporting Systems

Passive and active vaccine side effect reporting systems in countries around the world help to make sure that our vaccines are safe.

More on Global Vaccine Side Effect Reporting Systems

 

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