Side Effects and Adverse Events Following Immunizations

Vaccines are safe, but they do have some side effects, mostly mild, and they rarely cause some serious and severe adverse reactions.

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

To help keep our vaccines safe, it is important that all “clinically important adverse events that occur after vaccination of adults and children” be reported to VAERS, not just the ones that are known to be side effects.

Wait.

Isn’t an adverse event the same as a side effect?

Adverse Events Following Immunizations

To better understand that, let’s first look at how we define an adverse event following immunization (AEFI):

“An Adverse event following immunization (AEFI) is any untoward medical occurrence which follows immunization and which does not necessarily have a causal relationship with the usage of the vaccine. The adverse event may be any unfavourable or unintended sign, abnormal laboratory finding, symptom or disease.”

Classification of AEFIs

So it should be clear that not all adverse events are actually caused by vaccines.

Many are coincidental events that simply occur after a vaccine is given.

What’s the Difference Between Side Effects and Adverse Events Following Immunizations?

Others are true vaccine reactions though, including fever, pain, fainting, and allergic reactions, etc.

“A side effect is any health problem shown by studies to be caused by a vaccine. Like any medication, vaccines can cause side effects. Usually vaccine side effects are minor (for example, a sore arm where a shot was given or a low-grade fever after a vaccine) and go away on their own within a few days.”

Understanding Side Effects and Adverse Events

These are the reactions that we call side effects or adverse reactions of the vaccine.

Still, just because a sign or symptom can be a side effect of a vaccine doesn’t mean that it always will be.

“A vaccine reaction is an individual’s response to the inherent properties of the vaccine, even when the vaccine has been prepared, handled and administered correctly.”

Vaccine reactions – WHO Vaccine Safety Basics

Here are some other definitions:

  • adverse event – Medical occurrence temporally associated with the use of a medicinal product, but not necessarily causally related.
  • adverse reaction/side effect – A response to a drug which is noxious and unintended, and which occurs at doses normally used in man for the prophylaxis, diagnosis, or therapy of disease, or for the modifications of physiological function.
  • unexpected adverse reaction – Not consistent with applicable product information or characteristics of drug.
  • severe adverse event or reaction – are rarely life-threatening and usually do not result in long-term problems
  • serious adverse event or reaction – Any untoward medical occurrence that at any dose is life-threatening, results in death, requires inpatient hospitalization or prolongation of existing hospitalization, or results in persistent of significant disability or incapacity

Does understanding those definitions make it easier to see why you should be skeptical when folks try to scare you with VAERS reports and data from package inserts?

“Reports of all possible associations between vaccines and adverse events (possible side effects) are filed in VAERS. Therefore, VAERS collects data on any adverse event following vaccination, be it coincidental or truly caused by a vaccine. The report of an adverse event to VAERS is not documentation that a vaccine caused the event.”

Guide to Interpreting VAERS Data

They both can include reports about adverse events, not just side effects. So they both include events that can very well be coincidental, and not caused by a vaccine.

So when doing your research about vaccines, focus on real side effects, or things that are known to be caused by vaccines. You will find that most vaccine side effects are mild and that more serious or severe side effects are very rare.

More on Side Effects and Adverse Events

Are Vaccines Causing Long-Term Health Problems?

Did the CDC say that it is impractical to find out of vaccines are causing an epidemic of brain injury and other long-term health problems?

I’m guessing they didn’t…

Are Vaccines Causing Long-Term Health Problems?

Why does anyone think that they did?

The latest anti-vaccine propaganda about vaccines causing long-term health problems.
The latest anti-vaccine propaganda about vaccines causing long-term health problems.

Oh, anti-vaccine folks are sharing a cherry-picked quote from the CDC to scare parents away from vaccinating and protecting their kids.

Would you like to see the full quote?

“Observing vaccinated children for many years to look for long-term health conditions would not be practical, and withholding an effective vaccine from children while long-term studies are being done wouldn’t be ethical. A more practical approach is to look at health conditions themselves and at the factors that cause them. Scientists are already working to identify risk factors that can lead to conditions like cancer, stroke, heart disease, and autoimmune diseases such as lupus or rheumatoid arthritis. Thousands of studies have already been done looking at hundreds of potential risk factors. If immunizations were identified as a risk factor in any of these studies, we would know about it. So far, they have not.

We learn about a vaccine’s safety during clinical trials before it is licensed, and monitor it continually as millions of doses are administered after it is licensed. We also know there is not a plausible biologic reason to believe vaccines would cause any serious long-term effects. Based on more than 50 years of experience with vaccines, we can say that the likelihood that a vaccine will cause unanticipated long-term problems is extremely low.

Parents’ Guide to Childhood Immunizations

So no, the CDC didn’t say that it was impractical to find out of vaccines are causing an epidemic of brain injury.

Instead, they said that it was just impractical to do a study in which you give a child a vaccine and watch him for 20 years to see if he develops a problem, like leukemia, diabetes, or autism, all the while not giving the vaccine to other kids until your study is over. Of course, that’s because a lot of kids would get the potentially life-threatening disease that the vaccine is protecting those kids against while you were waiting to complete those long-term studies.

That’s not to say that we aren’t concerned about these types of long-term health problems occurring after a child is vaccinated.

Plenty of long-term safety studies have been done. It’s just more practical to do the studies on the diseases you are concerned about, sometimes after noticing safety signals, and see if vaccines truly are a risk factor.

Here is one example:

“In this large, population-based, case-control study, we did not find an increased risk of type 1 diabetes associated with any of the routinely recommended childhood vaccines.”

DeStefano et al on Childhood vaccinations, vaccination timing, and risk of type 1 diabetes mellitus.

In that study, they found all of the kids with diabetes born during 1988 through 1997 in the 4 health maintenance organizations (HMOs) that participate in the Vaccine Safety Datalink project of the Centers for Disease Control and Prevention, compared them to matched controls, and did not find an increased risk of type 1 diabetes associated with any of the routinely recommended childhood vaccines.

There are many more…

And that’s how we know vaccines aren’t causing long-term health problems.

Well at least those of us who did our research, looked for the original quote, and saw through this anti-vaccine propaganda.

More on Vaccines and Long-Term Health Problems

When is Measles Season?

For a while, especially once we eliminated the endemic spread of measles, we weren’t thinking about measles seasons anymore.

In addition to the recent rise in measles cases, this slide shows the patterns of measles seasons in different parts of the world.
In addition to the recent rise in measles cases, this slide shows the patterns of measles seasons in different parts of the world.

Unfortunately, with ongoing outbreaks and rising cases, many people are asking again – just when is measles season?

When is Measles Season?

Traditionally, the time when measles case counts are the highest occurs:

  • during the late winter and early spring (temperate climates, like the United States)
  • after the rainy season (tropical climates)
  • when kids are in school

So just like flu season, it’s always measles season somewhere…

And in areas of the world where measles is still highly endemic, you can expect cycles of larger measles epidemics every 1 to 4 years.

Can you guess why?

“As higher uniform population immunity is achieved the scale of epidemics, both their duration and absolute number of cases, progressively decreases. Epidemic frequency simultaneously decreases with increasing time intervals between epidemics. Another uniform feature as elimination is approached is the loss of epidemic seasonality.”

Durrheim et al on Measles – The epidemiology of elimination

I’ll give you a hint – there is nothing different about the measles virus during those years.

Eventually though, as the number of people susceptible to measles builds up, there is the opportunity for bigger outbreaks. Of course, that doesn’t happen if most people are vaccinated and protected.

When is Measles Season in the United States?

What about in the United States in the post-vaccine era?

Visiting a place with a lot of measles, especially if you aren't vaccinated and protected, increases the risk that you will bring measles home with you and start an outbreak.
Visiting a place with a lot of measles, especially if you aren’t vaccinated and protected, increases the risk that you will bring measles home with you and start an outbreak.

We don’t really have a measles season, as all of our cases are now imported from other parts of the world.

  1. Where and when are folks traveling?
  2. Where is measles on the rise?

That’s when we will see more measles cases here.

“Source countries included Philippines (14 cases), Ukraine (8), Israel (5), Thailand (3), Vietnam (2), Germany (2), and one importation each from Algeria, France, India, Lithuania, Russia, and the United Kingdom.”

Increase in Measles Cases — United States, January 1–April 26, 2019

In the early part of 2019, we saw a lot of cases because unvaccinated travelers were returning from Philippines, Ukraine, and Israel, countries in peak measles season.

Are Europe's measles outbreaks slowing down yet?
Are Europe’s measles outbreaks slowing down yet?

As cases in those countries hopefully slow down over the summer, unfortunately, we might see a rise in other parts of the world.

Of course, there is an easy way to end our measles seasons once and for all.

Two doses of MMR is your best protection against measles.

Get vaccinated and protected, especially before traveling out of the country.

More on Measles Season?

Are There Any Long-Term Studies On Vaccine Safety?

Vaccines are evaluated for safety in studies when they get approved.

Is that enough?

“I would like to see us do more long-term safety research studies on these large groups of children, so then we can determine that they are safe in the long-term.”

Bob Sears

Apparently not for everyone…

Are There Any Long-Term Studies On Vaccine Safety?

Of course, vaccines continue to be evaluated for safety after they approved, using passive and active vaccine safety systems and long-term post-marketing safety studies.

“We learn about a vaccine’s safety during clinical trials before it is licensed, and monitor it continually as millions of doses are administered after it is licensed. We also know there is not a plausible biologic reason to believe vaccines would cause any serious long-term effects. Based on more than 50 years of experience with vaccines, we can say that the likelihood that a vaccine will cause unanticipated long-term problems is extremely low.”

Parents’ Guide to Childhood Immunizations

These long term studies on vaccine safety have looked at:

Have you heard about these studies before?

When they talk about SV40, do anti-vaccine folks mention this long-term study?
When they talk about SV40, do anti-vaccine folks mention this long-term study?

Probably not.

Anti-vaccine folks either aren’t aware of, or just don’t want you to know about these types of long-term studies.

It’s easier to scare you away from vaccinating and protecting your kids if they make you believe that vaccines aren’t tested together, aren’t tested with placebos, aren’t tested vs unvaccinated kids, and aren’t tested for long periods of time.

They are!

More on Long-Term Studies On Vaccine Safety