Category: 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

What Is ADEM?

Have you ever heard of ADEM?

Most parents haven’t.

That’s probably good, because although you should be familiar with different things, if you know what it is, then you likely know someone who has been affected by it.

What Is ADEM?

ADEM, an autoimmune disease, is an acronym for Acute Disseminated Encephalomyelitis.

“Acute disseminated encephalomyelitis (ADEM) is characterized by a brief but widespread attack of inflammation in the brain and spinal cord that damages myelin – the protective covering of nerve fibers. ADEM often follows viral or bacterial infections, or less often, vaccination for measles, mumps, or rubella.”

Acute Disseminated Encephalomyelitis Information Page

Children and young adults with ADEM can have:

  • encephalopathy with confusion and irritability
  • hemiplegia – paralysis on one side of the body
  • ataxia – loss of full control of bodily movements leading to an unsteady walk
  • optic neuritis with vision impairment and vision loss
  • myelitis – inflammation in the spinal cord
  • speech impairment
  • hemiparesthesia – numbness on one side of the body and other sensory changes
  • seizures – especially in younger children

These symptoms typically follow a few days of fever, headache, nausea, vomiting, and feeling tired.

And to make the diagnosis, children with these symptoms of ADEM will have “focal or multifocal lesions predominantly involving white matter” on an MRI of their brain.

Fortunately, although ADEM can be life-threatening, there are treatments (steroids) for these kids and usually the outcome is good, with a complete or near complete recovery.

ADEM and Vaccines

Why do some folks associate ADEM with vaccines?

Mostly because some anti-vaccine websites like to try and associate ADEM with vaccines.

“ADEM is usually triggered by a preceding viral infection or immunization.”

Infection and Autoimmunity, Chapter 60

A lot of textbooks still list vaccines as a rare trigger too…

In this 2011 report, the IOM concluded that few health problems are caused by or clearly associated with vaccines.
In this 2012 report, the IOM concluded that few health problems are caused by or clearly associated with vaccines.

It is important to understand that ADEM most commonly occurs after a nondescript (not easily described), natural, viral or bacterial infection.

Interestingly, one of the first cases of ADEM was reported in 1790 – in a 23-year-old women who had just gotten over measles. Like many other serious complications of measles, ADEM is reported to occur after 1 in every 1,000 cases of measles.

What other infections can cause ADEM?

Most of them.

From HHV-6 (causes Roseola) and the coxsackievirus  (hand, foot, and mouth disease) to HIV and Dengue, they are all associated with ADEM. Many bacterial infections too, like Strep, Mycoplasma, and Salmonella.

“Older formulations of rabies vaccine did cause Acute Disseminated Encephalomyelitis (ADEM), but newer formulations of rabies vaccine have not been shown to cause ADEM, and rabies vaccine is not routinely recommended to the general population in the United States. Other vaccines that are currently routinely recommended to the general population in the U.S. have not been shown to cause ADEM.”

Institute for Vaccine Safety on Do Vaccines Cause Acute Disseminated Encephalomyelitis (ADEM)?

So what about vaccines?

Why do some folks still say that ADEM can follow getting vaccinated, especially after the 2012 IOM report on Adverse Effects of Vaccines: Evidence and Causality, found all of the evidence linking ADEM to vaccines “weak,” and in most cases, that the epidemiological evidence was “insufficient or absent to assess an association between” the vaccines and ADEM?

“Post vaccine aetiology was described for 5% of all ADEM cases and several vaccines have been described to be related to this condition. The incidence of ADEM onset ranges from 1/106 to 1/105 and may change between different vaccine formulations. Epidemiological data about this adverse event are still missing; this may be due to the rarity of post vaccine ADEM.”

Pellegrino et al on Acute Disseminated Encephalomyelitis Onset: Evaluation Based on Vaccine Adverse Events Reporting Systems

At most, ADEM is a very rare, 1 in a million type (1/106) vaccine reaction that is mainly published about in case reports and by reviewing VAERS.

Interestingly, no trigger is reported in up to 30% of cases (they don’t recall having a recent infection or getting a vaccine) and an infectious agent (a virus or bacteria) is usually not isolated from these children once they develop symptoms of ADEM.

“Epidemiologic evidence from this study suggests an infectious cause for ADEM. The agent is most likely a difficult-to-diagnose winter/spring respiratory virus.”

Murty et al on Acute Disseminated Encephalomyelitis in Children

Being so rare, it is hard to prove that ADEM absolutely isn’t caused by vaccines, but it does seem clear that many vaccine-preventable diseases might, from measles, mumps, rubella, chicken pox, flu, to hepatitis A.

Want to try and avoid ADEM? Get vaccinated.

What To Know About ADEM and Vaccines

Although vaccines have rarely been thought to cause Acute Disseminated Encephalomyelitis historically, it is very important to keep in mind that the overwhelming majority of cases of ADEM are caused by natural infections, many of which are vaccine preventable.

More About ADEM and Vaccines

Vaccine Reactions – Is This Normal?

Vaccines are very safe.

They are not 100% safe though and they can have some side effects.

“Considering that the vaccines in the infant schedule are administered to millions of children each year, the list of known adverse events, even rare ones, is impressively short.”

O’Leary et al on Adverse Events Following Immunization: Will It Happen Again?

Fortunately, most of these side effects are harmless and don’t have any long term risks. And of course, the great benefits of vaccines outweigh those risks.

Common Vaccine Reactions

Although most kids don’t have any reactions at all, some do have mild reactions.

Among the possible vaccine reactions or side effects that can occur include:

  • fussiness
  • headache
  • fever
  • body aches
  • redness or swelling at the injection site
  • soreness or tenderness at the injection site
  • tiredness
  • poor appetite
  • chills and sore joints
  • rash
  • diarrhea
  • vomiting
  • swelling of glands in the cheeks or neck

How commonly do they occur?

In this 2011 report, the IOM concluded that few health problems are caused by or clearly associated with vaccines.
In this 2011 report, the IOM concluded that “few health problems are caused by or clearly associated with vaccines.”

These side effects depend on the vaccine that was received and can range from 1 in 3 kids for some fussiness all the way down to 1 in 75 kids for kids who have swelling of their glands.

And they usually begin 1 to 3 days after the vaccine was given and last for 1 to 7 days.  Fortunately, fever and fussiness don’t last that long, typically going away after just a day or two.

Keep in mind that some reactions are more delayed though. This is especially true for the MMR vaccine, in which mild reactions, like a fever, rash, or swelling of glands might not occur until 6 to 14 days after a child got his vaccine.

What can you do if your child has a mild vaccine reaction?

Consult your health care provider, but keep in mind that treatment is often symptomatic, typically with a cold pack or cool cloth/compress for local reactions and pain reliever.

Fainting also commonly occurs after vaccines, especially in teens, but it is thought to be due to the vaccination process itself and not the vaccines. Still, it is something to be aware of.

What About More Moderate Reactions?

More moderate reactions after vaccines are fortunately more uncommon.

“There is low public tolerance of vaccine adverse reactions. Vaccines are therefore only licensed when the frequency of severe reactions is very rare and when only minor, self-limiting reactions are reported.”

WHO on Adverse events following immunization

Some of these moderate reactions might include:

  • febrile seizures
  • high fever
  • persistent crying for 3 or more hours
  • swelling of the entire arm or leg where the shot was given (especially after the 4th or 5th dose of DTaP)
  • a temporary low platelet count (immune thrombocytopenic purpura or ITP)

Like the more common, mild reactions, these less common moderate reactions are also temporary and don’t usually have any lasting risks or consequences.

Then there are the more severe reactions, which thankfully are even more rare. These are the 1 in a million dose type reactions, such as life-threatening allergic reactions.

Of course, you should seek medical attention if you think that your child is having a more moderate or severe reaction to a vaccine.

And lastly, there are the so-called vaccine induced diseases, which are simply made up.

All of these reactions, as well as the risks of getting a natural infection, are listed in each vaccine’s VIS. The Vaccine Information Statements also includes information on how to report all possible vaccine side effects to VAERS.

What to Know About Common Vaccine Reactions

While most kids don’t have any reactions at all after their vaccines, those that do typically have mild reactions, including some fever, soreness, or swelling at the injection site. More moderate and severe reactions are rare.

More About Common Vaccine Reactions

 

DTaP Vaccine Reactions – Is This Normal?

Vaccines are very safe.

They are not 100% safe though and they can have some side effects.

Fortunately, most of these side effects are harmless and don’t have any long term risks. And of course, the great benefits of vaccines outweigh those risks.

Common DTaP Vaccine Reactions

Although 75% of kids don’t have any reactions at all, some do have mild reactions.

Among the vaccine reactions or side effects that can occur most commonly include:

Vaccine Information Statements from the CDC highlight the risks of each vaccine.
The DTaP Vaccine Information Statement from the CDC highlight all of the vaccine’s possible risks.
  • fussiness
  • fever
  • redness or swelling at the injection site
  • soreness or tenderness at the injection site
  • tiredness
  • poor appetite
  • vomiting

How commonly do they occur?

They range from 1 in 3 kids for some fussiness all the way down to 1 in 50 kids for vomiting.

And they begin 1 to 3 days after the vaccine was given and last for 1 to 7 days.  Fortunately, fever and fussiness don’t last that long, typically going away after just a day or two.

Treatment is symptomatic, with a cold pack or cool cloth/compress and pain reliever

What About More Extensive Swelling and Redness?

Sometimes the swelling and redness after a DTaP vaccine can be more than you expect though. It might even make you think your child has developed a skin infection.

“Sometimes the 4th or 5th dose of DTaP vaccine is followed by swelling of the entire arm or leg in which the shot was given, lasting 1–7 days (up to about 1 child in 30).”

DTaP Vaccine Vaccine Information Statement

This more extensive local reaction, while scary looking, is not dangerous, and will also go away without long term effects.

It is also not an allergic reaction, so your child can finish the DTaP series if he or she still needs another dose.

Call your pediatrician or seek medical attention if you think your child has developed a skin infection after a vaccination, but keep in mind that bacterial cellulitis after getting a vaccine is an extremely rare, almost unheard of, complication.

Other more moderate and severe DTaP vaccine reactions are uncommon or rare.

“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

What about hypotonic-hyporesponsive episodes (HHE) and seizures? These were 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 remember that some so-called vaccine induced diseases are simply made up.

Most of these reactions, as well as the risks of getting natural diphtheria, tetanus, and pertussis infections, are listed in the DTaP VIS.

What to Know About Common DTaP Vaccine Reactions

While most kids don’t have any reactions at all after their DTaP vaccines, those that do typically have mild reactions, including some fever, soreness, or swelling at the injection site.

More About Common DTaP Vaccine Reactions

 

cVDPV

Circulating vaccine-derived polio virus or cVDPV are outbreaks of polio that are actually caused by the polio vaccine.

Very rarely, the attenuated (weakened) virus in the oral polio vaccine can revert to a form that can cause the person who was vaccinated or their close contact to actually develop polio.

It should not be confused with VAPP or vaccine-associated paralytic polio. With VAPP, the original strain of attenuated vaccine virus reverts to a form that can cause polio, but it does spread from one person to another, so does not lead to outbreaks.

cVDPV Outbreaks

Fortunately, both VAPP and cVDPV are rare.

How rare? VAPP only occurs in about 1 in every 1.27 million children receiving their first dose of OPV.

And according to the WHO, there had only been about 24 outbreaks of cVDPV over the past 10 years. Tragically, this has resulted in at least 750 cases of paralytic polio in 21 countries.

An outbreak of cVDPV in Syria will be controlled by 355 vaccination teams that will vaccinate up to 328,000 children.
The WHO reports that an outbreak of cVDPV in Syria will be controlled by 355 vaccination teams that will vaccinate up to 328,000 children.

A new outbreak of cVDPV in Syria adds to those numbers though.

After being polio free for 15 years, since 1999, Syria began having cases of wild type polio again in 2013 (35 cases) and 2014 (1 case). Those polio cases and the emergence of an outbreak of cVDPV2 (there are three strains of polio virus – this outbreak was caused by the type-2 strain) highlight the effects of years of poor immunization rates because of war.

While there are many challenges to getting kids vaccinated in Syria, up to 355 vaccination teams with 61 supervisors will be working out of five vaccine distribution centers to vaccinate 328,000 children to control the outbreak and get kids vaccinated.

Circulating Vaccine-Derived Polio Virus

Just like wild type polio, we can stop cVDPV by increasing vaccination rates and increasing access to improved sanitation facilities.

Why?

Although anti-vaccine folks routinely cry wolf about shedding, the oral polio vaccine really does shed – in the stool of people who have been recently vaccinated. You can then be exposed to the attenuated polio vaccine virus (which can help give immunity to others in the community by passive immunization) or a strain of cVDPV (which can, unfortunately, help give others, especially if they are not vaccinated, paralytic polio) if they are exposed to open sewage or can not practice proper hygiene, etc.

Can’t we just stop using the live, oral polio vaccine?

Although a serious side effect of the vaccine, the vaccine’s benefits clearly outweigh the risk of both VAPP and cVDPV while polio is endemic (lots of cases) in a region, after all, without the vaccine, hundreds of thousands of children would get polio and would be paralyzed.

In polio-free countries, the risks of VAPP and cVDPV becomes greater than the risk of polio though, and they move to the inactivated polio vaccine. That helps prevent a situation in which the polio vaccines actually causes more cases of polio than wild type polio viruses.

Eventually, all countries will move to the IPV vaccine as we move closer to polio eradication. We came one step closer to that point in April 2016 when all countries that were still using the oral polio vaccine switched from trivalent OPV (three strains) to bivalent OPV (two strains) for their routine immunization programs. This could eliminate up to 90% of cases of cVDPV (most are caused by the type-2 strain which is not in bOPV)!

What To Know About cVDPV

Circulating vaccine-derived polio virus outbreaks are a rare side effect of the oral polio vaccine.

More Information About cVDPV

Vaccines and Seizures

A newborn baby getting an EEG.
A newborn baby getting an EEG.

Can vaccines cause seizures?

Unfortunately, they sometimes can.

Vaccines and Febrile Seizures

The CDC reports that “There is a small increased risk for febrile seizures after MMR and MMRV vaccines.”

We also know that:

  • there is a small increased risk for febrile seizures when the influenza vaccine is given at the same time as either the Prevnar13 vaccine or the DTaP vaccine, although “the risk of febrile seizure with any combination of these vaccines is small and CDC’s Advisory Committee on Immunization Practices (ACIP) does not recommend getting any of these vaccines on separate days.”
  • there is a small increased risk for febrile seizures if the combined MMR and chicken pox vaccine (ProQuad) is given to infants between the ages of 12 to 23 months vs their getting the shots separately.

But remember that febrile seizures, while scary for parents and other caregivers, are rarely dangerous.

It is also important to note that while febrile seizures are common, they are not commonly triggered by vaccines. A 2016 report in Pediatrics, “Vaccines and Febrile Seizures: Quantifying the Risk,” states that “The risk is 1 febrile seizure per pediatric practice every 5 to 10 years.”

Not surprisingly though, vaccines can likely prevent many febrile seizures, as chicken pox, flu, Hib, measles, mumps, rubella, pneumococcal infections and other vaccine-preventable diseases often cause fever and can trigger febrile seizures themselves.

Also, a study recently found that children who got sick with pertussis could be at increased risk for developing epilepsy, or recurrent seizures. That’s just another good reason to get vaccinated and protected against vaccine-preventable diseases.

Vaccines and Other Types of Seizures

While vaccines can sometimes trigger febrile seizures, they do not typically cause other types of seizures.

It was once thought that seizures were a common side effect of the DPT vaccine, but many studies have found that to not be true and seizures following DPT was even removed as a table injury from the NVICP. In fact, many of these children were instead found to have Dravet syndrome, which put them at increased risk for febrile seizures.

Long-term non-febrile seizures are still listed as side effects for the DTaP and MMR vaccine, but they “are so rare it is hard to tell if they are caused by the vaccine.”

A 2010 study in Pediatrics, “Lack of Association Between Acellular Pertussis Vaccine and Seizures in Early Childhood,” did not find any “increased risk for seizures after
DTaP vaccination among children who were aged 6 weeks to 23 months.”

Do report any reaction to VAERS if you think it was caused by a vaccine though.

Seizures After Getting Vaccines

If vaccines don’t usually cause seizures, then how do you explain a healthy infant developing seizures a few days, weeks, or months after getting his vaccines?

We’re always looking for reasons why something happened. The example I use is from my wife, who is a pediatrician. She was about to vaccinate a four-month-old baby, and while she was drawing the vaccine from the syringe, the baby had a seizure — and went onto have a permanent seizure disorder. Now, my wife hadn’t given the vaccine yet. But if she had given that vaccine five minutes earlier, there would have been no amount of statistical data in the world that would have convinced that mother that the vaccine hadn’t caused the baby’s seizure. You can do studies that show no increased risk with vaccines and seizure disorders, but that mother might still say “well, that’s true for the population but it’s not true for my child.”

Temporal associations are powerful, and they’re hard to defeat with statistics or studies.

Paul Offit, MD interview for The Thinking Persons Guide to Autism

There are many seizure disorders that begin in infancy.

Some even start in the newborn period, before a baby is a month old.

They are not triggered by vaccines though.

They include:

  • Infantile Spasms (first described in 1841) – typically begin when infants are about 4 months old, just when they get their second set of vaccines, which weren’t available when Dr. West described his own son’s repeated spasms
  • Benign Familial Neonatal Seizures – often genetic, seizures may begin on a baby’s third day of life
  • Benign Neonatal Convulsions – begin on the fifth day of life – the “fifth day fits,” and the seizures stop in about a month

If your child got her first hepatitis B vaccine when she was five days old and began having seizures, would you accept a diagnosis of Benign Neonatal Convulsions or would you blame the shot?

Would you remember the saying about correlation and causation?

For More Information on Vaccines and Seizures: