Category: Vaccine Safety

Is It a Vaccine Reaction?

Why do anti-vaccine folks think that there are so many vaccine reactions?

It is mostly because they think that anything bad that happens after someone is vaccinated, even if it is weeks or months later, must have been caused by the vaccine.

“Differentiation between coincidence and causality is of utmost importance in this respect. This is not always easy, especially when an event is rare and background rates are not available.”

Heininger on A risk-benefit analysis of vaccination

Of course, this discounts that fact that most people have a basic risk, often called the background rate, for developing most of these very same conditions, and they can just coincide with getting vaccinated.

Put more simply, the “reaction” would have happened whether or not they had been vaccinated.

“…when a number of well-controlled studies were conducted during the 1980s, the investigators found, nearly unanimously, that the number of SIDS deaths temporally associated with DTP vaccination was within the range expected to occur by chance. In other words, the SIDS deaths would have occurred even if no vaccinations had been given.”

WHO on Six Common Misconceptions About Immunization

That doesn’t mean that everything automatically gets blamed on coincidence though.

Is It a Vaccine Reaction?

Vaccine adverse events can be reported to VAERS online or using a downloadable form.
Vaccine reactions can be reported to VAERS online or using a downloadable form.

When trying to determine if a child has had a vaccine reaction, experts typically go through a series of questions, looking at the evidence for and against :

  • How soon after the vaccine was given did the reaction occur? Was it minutes, hours, days, weeks, months, or years later?
  • Is there any evidence that something else could have caused the reaction?
  • Is there a known causal relation between the reaction and the vaccine?
  • Is the reaction a table injury?
  • Is there evidence that the vaccine does not have a causal association with the reaction?
  • Do any lab tests support the idea that it was a vaccine reaction?

Why is it important to consider these and other questions?

Because most of us are very good at jumping to conclusions, are quick to place blame, and like to know the reasons for why things happen.

We don’t like to think that things are just caused by coincidence.

Post hoc ergo propter hoc (after this, therefore, because of this).

We are especially good at linking events and often automatically assume that one thing caused another simply because it occurred afterwards.

It is incident to physicians, I am afraid, beyond all other men, to mistake subsequence for consequence.

Dr Samuel Johnson

But we also know that correlation does not imply causation. And because of the great benefits of vaccines, it is important to find strong evidence for a correlation before we blame vaccines for a reaction.

Too often though, the opposite happens. Despite strong evidence against a correlation, parents and some pediatricians still blame vaccines for many things, from SIDS and encephalitis to autism.

Background Rates vs Vaccine Reactions

Although anti-vaccine folks are always calling for vaccinated vs unvaccinated studies to further prove that vaccines are indeed safe, much of that work is already done by looking at the observed rate of possible reactions and comparing them to the background rate of reactions and conditions.

We often know how many people are expected to develop certain conditions, from seizures and type 1 diabetes mellitus to acute transverse myelitis and juvenile and rheumatoid arthritis.

“On the basis of the reviewed data, if a cohort of 10 million individuals was vaccinated in the UK, 21.5 cases of Guillain-Barré syndrome and 5.75 cases of sudden death would be expected to occur within 6 weeks of vaccination as coincident background cases. In female vaccinees in the USA, 86.3 cases of optic neuritis per 10 million population would be expected within 6 weeks of vaccination. 397 per 1 million vaccinated pregnant women would be predicted to have a spontaneous abortion within 1 day of vaccination.”

Black et al on Importance of background rates of disease in assessment of vaccine safety during mass immunisation with pandemic H1N1 influenza vaccines

Intussusception is a good example of this.

This might surprise some folks, but we diagnosed and treated kids with intussusception well before the first rotavirus vaccines were ever introduced. And then, it was only after the risk of intussusception after vaccination exceeded the background rate that experts were able to determine that there was an issue.

Background rates also explain why unvaccinated kids develop autism. It’s not a coincidence.

“Knowledge of the background incidence rates of possible adverse events is a crucial part of assessing possible vaccine safety concerns. It allows for a rapid observed vs expected analysis and helps to distinguish legitimate safety concerns from events that are temporally associated with but not necessarily caused by vaccination.”

Gadroen et al on Baseline incidence of intussusception in early childhood before rotavirus vaccine introduction, the Netherlands, January 2008 to December 2012

Fortunately, studies have never found an increased risk above the background rate for SIDS, non-febrile seizures, and other things that anti-vaccine folks often blame on vaccines. So when these things happen on the same day or one or two days after getting vaccinated, it almost certainly truly is a coincidence. It would have happened even if your child had not been vaccinated, just like we see these things happen in the days before a child was due to get their vaccines.

For example, using background incidence rates in Danish children, one study found that if you vaccinated a million children with a new flu vaccine, you could expect that naturally, after seven days, you would see:

  • facial nerve palsy – one case
  • seizures – 36 cases
  • multiple sclerosis – one case
  • type 1 diabetes – three cases
  • juvenile and rheumatoid arthritis – three cases

After six weeks, those numbers of course go up. In addition to 4 kids developing MS, 20 develop diabetes, 19 develop arthritis, and 218 have seizures, and there would have been at least two deaths of unknown cause.

Would you blame the flu shot for these things?

What flu shot?

This was a “hypothetical vaccine cohort” that used 30 years of data from the Danish healthcare system to figure out background rates of each condition.

“In addition, the expected number of deaths in Japan following an estimated 15 million doses of H1N1 vaccine administered would be >8000 deaths during the 20 days following vaccination, based on the crude mortality rate.”

McCarthy et al on Mortality Rates and Cause-of-Death Patterns in a Vaccinated Population

Looking at background rates is especially helpful when folks report about vaccine deaths.

Using the Japan example that McCarthy studied, if they had looked at background rates, then all of a sudden, the 107 deaths they found after 15 million doses of H1N1 vaccine were given in 2009 would not have been so alarming. Background rates would have predicted a much, much higher number of deaths to naturally occur in that time period simply based on crude mortality rates.

Again, none of this means that possible vaccine reactions are dismissed as being coincidences. They just aren’t immediately assumed to have been caused by vaccines, because vaccines are necessary and a lot of research has already gone into demonstrating that vaccines are safe and vaccines continue to go through routine safety monitoring to make sure they stay safe.

What to Know About Evaluating Vaccine Reactions

Vaccines are safe and many of the things that folks think are vaccine reactions can be explained by looking at the background rates for these conditions and understanding that they would have happened anyway.

More on Evaluating Vaccine Reactions

Vaccines are Safe

Vaccines have side effects.

Fortunately, they are usually very mild.

And understanding that vaccines are safe, makes getting their kids vaccinated an easy decision for most parents, as they understand that the many benefits of vaccines far outweigh any possible risks.

How Do We Know Vaccines Are Safe?

If you are on the fence about vaccines, simply saying they are safe might not be enough for you.

“​Over the previous 40 years the IOM has conducted over 60 vaccine safety studies, including this comprehensive review of the immunization schedule. The IOM committee did not find any evidence of major safety concerns related to receiving on-time vaccinations according to the Recommended Immunization Schedule for children. They concluded that this should help to reassure stakeholders. Further, they noted that while the receiving on-time vaccines was not harmful, it was strongly associated with reducing vaccine-preventable diseases. ​”

American Academy of Pediatrics on Vaccine Safety: Examine the Evidence

How do we really know vaccines are safe?

A 2013 report about vaccines from the Institute of Medicine uncovered no evidence of major safety concerns.
A 2013 report about vaccines from the Institute of Medicine uncovered no evidence of major safety concerns.
  • vaccines go through a long period of pre-licensure testing and evaluation when being developed to make sure they are safe and that they work before they are approved
  • vaccines are tested together
  • vaccines are continually monitored after they are made, to make sure they maintain their potency, are kept at the proper temperature, and other quality testing
  • several post-licensure vaccine safety systems monitor for safety issues, including VAERS, the Vaccine Safety Datalink, and the Clinical Immunization Safety Assessment (CISA) Project and other global vaccine safety systems
  • 40 years of safety reports from the Institute of Medicine (IOM)
  • reports from the Global Advisory Committee on Vaccine Safety, which has reviewed and commented on everything from aluminum adjuvants and the potential for immunogenic overload (too many too soon) to the safety of HPV vaccines

And it is important to know that much of the information that you hear and read that is trying to scare you about vaccines and vaccine ingredients is simply not true and easily debunked.

What to Know About Vaccine Safety

From years and years of pre-licensure vaccine safety testing to continual post-licensure vaccine safety monitoring, we can be confident that vaccines are safe.

More on Knowing Vaccines are Safe

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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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Vaccines and Encephalitis

It is thought that vaccines can, very rarely, cause encephalitis.

“Encephalitis: Irritation and swelling (inflammation) of the brain, most often due to infections.”

IOM Report on Adverse Effects of Vaccines

Encephalitis is actually a table injury in the National Vaccine Injury Compensation Program if it occurs:

  • within 72 hours of getting a pertussis containing vaccines
  • within 5 to 15 days of getting an MMR vaccine

And since it is a table injury, then unless another cause is found, “it is presumed that the vaccine was the cause of the injury.”

Most causes of encephalitis are natural infections, including some that are vaccine-preventable. In fact, about 1 in 1,000 people who get measles can develop measles encephalitis.

So the fact that vaccines can, very rarely, cause encephalitis, shouldn’t lead anyone to think that delaying or skipping a vaccine is a good idea.

Autism and Encephalitis

Of course, it isn’t that simple.

The problem?

The misnamed Immunity Education site tries to scare parents into thinking that crying, even excessively, after a vaccine means a child has encephalitis.
The misnamed Immunity Education site tries to scare parents into thinking that crying, even excessively, after a vaccine means that a child has encephalitis.

Anti-vaccine folks claim that an awful lot of things are encephalitis, from crying excessively after getting a vaccine to autism.

Although the Vaccine Information Statement for the DTaP vaccine (it was more common after the older DTP vaccine) does state that children may uncommonly have “non-stop crying, for 3 hours or more” it is not because they have brain inflammation, and the reaction “although unnerving, is otherwise benign.” It is not even a contraindication to getting another dose of DTaP or a later dose of Tdap.

What causes this non-stop crying? It is thought to be a painful local reaction. Fortunately, it does not happen as often with the newer DTaP vaccines.

And autism is not encephalitis.

“That measles infections can cause neurologic side effects on rare occasions is known, but the complication rate for vaccinations is low. After infectious measles encephalitis, risk of an autistic regression has occurred in 1/1000 to 1/10,000 cases. If the trend toward delaying vaccination continues because parents remain misinformed about the MMR, the number of children with neurologic complications of measles or rubella will increase. ”

Chez et al on Immunizations, Immunology, and Autism

Can encephalitis lead a child to have symptoms of autism?

Sometimes.

In addition to natural measles infections, there have been reports of children developing autism after HSV encephalitis, varicella encephalitis, congenital rubella syndrome, and congenital syphilis.

But the great majority of kids with autism do not first have encephalitis. They do not have ongoing brain inflammation.

Saying that encephalitis can cause autism is not the same thing as saying that autism is encephalitis.

Do Vaccines Cause Encephalitis?

And even though encephalitis has long been a table injury for a few vaccines, the 2012 IOM report, “Adverse Effects of Vaccines: Evidence and Causality,” found inadequate evidence to be able to conclude that encephalitis was caused by vaccines.

“Follow-up investigations in that cohort and others, however, found no evidence of a real increased incidence of encephalitis following DTwP. In addition, the most recent IOM report concludes that the evidence is inadequate to accept or reject a causal relationship between diphtheria toxoid-, tetanus toxoid-, or acellular pertussis-containing vaccine and encephalitis or encephalopathy.”

Vaccinophobia and Vaccine Controversies of the 21st Century

That’s not surprising, because follow-up of children studied in the 1980s, from which the original claims about DTP and encephalitis were made, found no evidence of an increased risk of encephalitis.

What about the MMR vaccine?

Again, the IOM report found inadequate evidence, but the problem has always been that “acute encephalitis post-MMR is so rare that it has been impossible to distinguish from the background encephalitis rate of 1 in one million in immune competent hosts.”

Anti-NMDAR Encephalitis

Doesn’t the discovery of anti-N-methyl-D-aspartate (anti-NMDA) receptor encephalitis prove that vaccines cause autism?

“Anti-NMDA receptor encephalitis is a disease occurring when antibodies produced by the body’s own immune system attack NMDA receptors in the brain.”

The Anti-NMDA Receptor Encephalitis Foundation

Often associated with tumors, isolated case reports do correlate anti-NMDAR encephalitis with vaccines. There are so few cases of anti-NMDAR encephalitis though, it is hard to know what they mean, as are the reports of autism developing after anti-NMDAR encephalitis.

What to Know About Vaccines and Encephalitis

Vaccines still don’t cause autism and the latest safety studies report that vaccines probably don’t cause encephalitis, although a few are still listed as a table injury.

More About Vaccines and Encephalitis

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IOM Vaccine Reports

The Institute of Medicine (IOM) is an independent, nonprofit organization that works outside of government to provide unbiased and authoritative advice to decision makers and the public.

“With the start of the new school year, it’s time to ensure that children are up to date on their immunizations, making this report’s findings about the safety of these eight vaccines particularly timely,” said committee chair Ellen Wright Clayton, professor of pediatrics and law, and director, Center for Biomedical Ethics and Society, Vanderbilt University, Nashville, Tenn.  “The findings should be reassuring to parents that few health problems are clearly connected to immunizations, and these effects occur relatively rarely.  And repeated study has made clear that some health problems are not caused by vaccines.”

They occasionally issue reports and safety reviews about vaccines:

Reading these reports will help you to understand why vaccine experts argue that vaccines do not cause autism, SIDS, or multiple sclerosis, etc.

For More Information On IOM Vaccine Reports:

Vaccine Safety

Although vaccines can have some risks and  mild or even moderate side effects and very rarely cause more severe reactions, vaccines are safe and necessary to keep your kids protected against vaccine-preventable diseases.

Vaccine Safety

Vaccines go through a long process of development and testing to make sure they are safe before they are approved.

“Vaccine development is a long, complex process, often lasting 10-15 years and involving a combination of public and private involvement.”

The History of Vaccines on Vaccine Development, Testing, and Regulation

But it doesn’t stop then.

We continue to see testing and monitoring for vaccine safety:

  • by monitoring the potency of vaccines after they are manufactured
  • by monitoring the temperatures of the vaccines while they are being shipped and stored
  • continuing to do quality testing, even after the vaccine is released
  • using phase 4 trials and with our post-licensure vaccine safety systems, including VAERS, the Vaccine Safety Datalink, and the Clinical Immunization Safety Assessment (CISA) Project

All of this testing and monitoring has led to some vaccine recalls and the withdrawal of the original rotavirus vaccine because of its association with intussusception.

What to Know About Vaccine Safety

Vaccines are well tested and monitored for safety, both before they are approved and after.

More on Vaccine Safety

Updated October 21, 2017

NVICP

The National Vaccine Injury Compensation Program (NVICP) was created by the National Childhood Vaccine Injury Act of 1986 following years of often frivolous lawsuits against vaccine manufacturers and health professionals, even though similar lawsuits in the UK against vaccine manufacturers failed to find that the DPT vaccine caused vaccine injuries.

The NVICP was created as “a no-fault alternative to the traditional legal system for resolving vaccine injury petitions.”

Those who think they have suffered a vaccine injury can file a petition with the U.S. Court of Federal Claims – the Vaccine Court. A court-appointed special master eventually decides if the claim should be compensated or dismissed.

For more information: