Category: Vaccine Safety

Why Can’t You Give Blood After Getting a Vaccine?

If you are like most people, you have heard so much anti-vaccine misinformation that you figure it is safe to assume that everything these folks say isn’t true.

Yes, go research shedding

If you are a true skeptic, you will still do your research on any new claims just to make sure.

Why Can’t You Give Blood After Getting a Vaccine?

Although you may not have heard of any restrictions on donating blood after getting vaccinated before, it makes sense once you think of it.

You actually have to wait:

  • for up to 8 weeks after getting the smallpox vaccine
  • for up to 4 weeks after getting the MMR (because of the rubella component), chickenpox, and Zostavax vaccines.
  • for up to 3 weeks after getting the hepatitis B vaccine
  • for up to 2 weeks after getting the measles, mumps, oral polio, or yellow fever vaccines

If you notice that these are almost all live vaccines, it becomes very easy to see why you can’t donate blood shortly after being vaccinated.

Blood donation is “Acceptable if you were vaccinated for influenza, tetanus or meningitis, providing you are symptom-free and fever-free. Includes the Tdap vaccine. Acceptable if you received an HPV Vaccine (example, Gardasil).”

American Red Cross Eligibility Criteria: Alphabetical

Live vaccines can create a temporary viremia (virus particles in the blood), which could then be transferred to someone else in donated blood.

Could you get an infection this way?

Probably not.

Remember, you would only be getting the attenuated or weakened vaccine virus strain and even then, it would be a very small amount. If the person getting the vaccine doesn’t get sick from getting the vaccine, why would someone who was getting a much smaller dose through a blood donation.

Still, there is a theoretical risk, especially if the person who received the blood donation had an immunodeficiency, so people aren’t supposed to donate blood shortly after getting these vaccines.

But what about the hepatitis B vaccine. It isn’t a live virus vaccine.

The risk with this vaccine is that a very recently vaccinated donor might test positive for HBsAg (this only happens temporarily), leading the donation center to actually think that they had a hepatitis B infection, disqualifying them from ever donating blood again.

Does any of this mean that vaccines aren’t safe?

Of course not!

Just consider some of the other restrictions on donating blood:

  • You are not eligible to ever donate if you ever tested positive for hepatitis B, even if you were never sick.
  • You must wait 12 months after your last contact if you were exposed to someone with hepatitis B and you want to donate blood.
  • If you are unvaccinated, you must wait at least 4 weeks after being exposed to someone with measles.

So yes, that means that you will be much more likely to be eligible to donate blood if you are fully vaccinated and protected.

More on Donating Blood After Getting Vaccinated

What Is the Morbidity/Mortality Rate of the Polio Vaccine vs the Wild Virus?

Some anti-vaccine folks still think that the risks of vaccines are far greater than the risks of the vaccine-preventable diseases they keep you from getting.

As more people are vaccinated and diseases disappear, they forget how bad those diseases are, skip or delay getting their vaccines, and trigger outbreaks.
As more people are vaccinated and diseases disappear, they forget how bad those diseases are, skip or delay getting their vaccines, and trigger outbreaks. Photo by WHO

They aren’t, but you can kind of understand why they might think that with a disease like polio, when they might never actually have known anyone to have the disease.

What Is the Morbidity/Mortality Rate of the Polio Vaccine vs the Wild Virus?

Still, even though polio is under good control and close to being eradicated, the risk/benefit ratio clearly favors getting vaccinated and protected.

That’s because the polio vaccines are very safe and if we stopped vaccinating, polio could come back.

In fact, morbidity/mortality from polio vaccines are decreasing, as we are using much less oral polio vaccine (OPV) in the transition (OPV cessation) to just using inactivated polio vaccine (IPV).

“Over the past ten years, more than 10 billion doses of OPV have been given to nearly three billion children worldwide. More than 16 million cases of polio have been prevented, and the disease has been reduced by more than 99%. It is the appropriate vaccine through which to achieve global polio eradication.”

OPV Cessation

And while most developed countries already use IPV, those that are still using OPV recently switched from a trivalent (tOPV) to a bivalent (bOPV) form of OPV. We could do this because type 2 poliovirus has already been eradicated (2015)!

Of course, the issue with the OPV vaccines is that they rarely cause vaccine-associated paralytic polio (VAPP) and circulating vaccine-derived polioviruses (cVDPV).

Fortunately, this is even less common with bOPV.

As this chart from the WHO shows, polio vaccines are very safe.
As this chart from the WHO shows, polio vaccines are very safe.

So morbidity (getting sick)/mortality (dying) from polio vaccines is low.

There were only 31 cases of wild polio in 2018, in Afghanistan and Pakistan, and an additional 102 cases of cVDPV in 7 countries.

What about morbidity/mortality from polio?

“As recently as 30 years ago, wild poliovirus paralysed more than 350 000 children in more than 125 countries every year. In 2018 there were fewer than 30 reported cases in just two countries – Afghanistan and Pakistan.”

“Zero polio transmission and health for all”, WHO Director-General gives new year’s wish to the people of Afghanistan and Pakistan

With a 99.9% drop in polio cases since 1998, your risk of getting polio in most parts of the world is very low, but you still have to consider both the morbidity/mortality of polio in the pre-vaccine era and the risk of polio returning if we stop vaccinating before it is eradicated.

What about the idea that you don’t have to worry about polio because only 1% of kids with polio developed paralysis?

“The mortality rate for acute paralytic polio ranges from 5–15%.”

Disease factsheet about poliomyelitis

Well, when everyone gets polio, even 1% is a lot.

With such a safe vaccine, why put your kids at risk of getting polio?

Do you even understand what the risks are?

No, it isn’t just the risk of wild polio in Afghanistan and Pakistan.

Since the oral polio vaccines shed, if you are unvaccinated, in addition to the risk of wild polio, there is a small risk of getting circulating vaccine-derived polioviruses (cVDPV) if you are not vaccinated and protected. No, it is not a big risk, as there were only 102 cases of cVDPV in 7 countries in 2018, but it isn’t zero either.

And the other big risk is that if enough folks stop getting vaccinated, taking their chances hiding in the herd, polio will come back and our chance to eradicate another vaccine-preventable disease will fail.

More on the Morbidity and Mortality Rates of Polio

Can Your Kids Get a Vaccine While They Are Taking Antibiotics?

In general, simply taking an antibiotic would not usually be a reason to not get vaccinated.

“Contraindications and precautions to vaccination generally dictate circumstances when vaccines will not be given. Many contraindications and precautions are temporary, and the vaccine can be given at a later time.”

General Recommendations on Immunization

The reason your child is taking the antibiotic could make you want to think about delaying the vaccine though.

Can Your Kids Get a Vaccine While They Are Taking Antibiotics?

Kids are prescribed antibiotics for a lot of different reasons, from treating ear infections and acne to pneumonia and meningitis.

Since a mild acute illness with or without fever isn’t considered a contraindication or precaution to getting vaccinated, in most cases, being on an antibiotic would not cause you to want to skip or delay your child’s vaccines.

The vaccine information sheet that you get with each vaccine will list contraindications and precautions on who should not get the vaccine.
The vaccine information sheet that you get with each vaccine will list contraindications and precautions on who should not get the vaccine.

In fact, current antimicrobial therapy is listed by the CDC as one of the conditions commonly misperceived as a contraindication or precaution!

There are some exceptions though, including:

  • taking the antibiotic for a moderate or severe acute illness with or without fever (a general precaution to getting a vaccine)
  • antimalarial agents and antibiotics might interfere with the Ty21a oral typhoid vaccine
  • antiviral drugs (acyclovir, famciclovir, or valacyclovir) might interfere with varicella-containing vaccines (Varivax)
  • antiviral drugs (Tamiflu, Relenza) might interfere with LAIV4 (FluMist, the nasal spray flu vaccine)

Is your child taking the antibiotic for a mild illness or a more moderate or severe illness for which they are now recovering? Then the fact that they are still taking an antibiotic likely isn’t a contraindication or a precaution to getting vaccinated.

More on Vaccine Contraindications

VigiAccess Numbers in Context

Most people are familiar with VAERS, the Vaccine Adverse Event Reporting System.

They sometimes forget that it is only the Vaccine Adverse Event Reporting System for the United States.

Other countries have their own vaccine safety systems.

VigiAccess Numbers in Context

One of the biggest is VigiBase, the World Health Organization’s  global database for suspected adverse drug reactions, maintained by the Uppsala Monitoring Centre in Sweden.

“Information on suspected ADR should not be interpreted as meaning that the medicinal product in question, or the active substance(s), generally causes the observed effect or is unsafe to use.”

Not surprisingly, folks misuse VigiBase numbers, just like they misuse VAERS reports.

JB Handley needs help understanding VigiAccess reports.
JB Handley needs help understanding VigiAccess reports.

To look at the VigiBase reports, you can use VigiAccess.

“VigiAccess has a search interface that allows visitors to retrieve summary statistics on suspected adverse reactions to medicines and vaccines.”

Uppsala Monitoring Centre

While VigiBase “is at the heart of UMC’s signal detection and scientific research,” you aren’t going to learn much from VigiAccess.

“Geographically, only continent-level statistics are shown, due to issues relating to patient confidentiality and data protection in individual countries.”

Uppsala Monitoring Centre

The biggest problem?

You don’t know how many vaccines were given to all of those people.

For example, while it might sound like there have been a lot of adverse drug reaction reports for the DTaP vaccine, with 179,447 reports in VigiAccess, since those are worldwide reports since 1968, it is likely among many billions of doses of vaccines being given.

Most importantly though, as with VAERS, “The reports in VigiBase result from suspicions of a relationship between a drug and a reaction. No causal relation has been confirmed.”

So how do you put the numbers from VigiBase and VigiAccess in context?

If you consider that reports and safety signals from VigiBase, VigiMatch, VigiRank, and other tools used by the Uppsala Monitoring Centre continue to find that vaccines are safe, then to put the DTaP numbers in context, they help us know that vaccines are being well monitored for safety.

And since we know that these diseases haven’t disappeared, any further context, if you need it, would be that since vaccines are safe and necessary, then you should get yourself and your family vaccinated and protected.

More on VigiBase and VigiAccess

 

Can Vaccines Cause Kawasaki Disease?

Kawasaki disease is rare and there is a good chance that you have never even heard of it, even though the first case was diagnosed in 1961.

Kids with this condition are typically irritable and can develop high fever, swollen glands in their neck, red eyes, red, cracked lips, red, swollen hands and feet, and a rash.

If you have heard of it, there is a good chance it is because anti-vaccine folks are using Kawasaki disease to scare you away from vaccinating and protecting your kids. Lately, talk about Kawasaki disease and the meningococcal B vaccines have been going around.

What Causes Kawasaki Disease?

Kawasaki disease is a type of vasculitis.

Kids who develop Kawasaki disease, who are typically under age 5 years, develop inflammation of their blood vessels, which leads to many of the symptoms and complications we see.

What causes this inflammation?

“Evidence suggests that Kawasaki disease may be linked to a yet-to-be identified infectious agent, such as a virus or bacteria. However, despite intense research, no bacteria, virus, or toxin has been identified as a cause of the disease.”

AAP on Kawasaki disease

We don’t know.

Can Vaccines Cause Kawasaki Disease?

Ask about Kawasaki disease if your child has a fever for five days and other symptoms of Kawasaki disease.
Courtesy of the kdfoundation.org

Because the cause of Kawasaki disease is unknown, that leads some folks to think that it could be vaccines.

Could it?

That vaccine clinical trial data sometimes finds a higher, although not statistically significant risk for Kawasaki disease, gets some of those folks thinking about it even more, except they don’t seem to think about the fact that the risk is never statistically significant.

But aren’t there case reports of kids getting Kawasaki disease after getting a hepatitis A, yellow fever, hepatitis B, or flu vaccine?

Yes, but getting a case report published about one patient who you think got Kawasaki disease soon after getting a vaccine isn’t strong evidence that it wasn’t a coincidence.

“Childhood vaccinations’ studied did not increase the risk of Kawasaki disease; conversely, vaccination was associated with a transient decrease in Kawasaki disease incidence. Verifying and understanding this potential protective effect could yield clues to the underlying etiology of Kawasaki disease.”

Abrams et al. on Childhood vaccines and Kawasaki disease, Vaccine Safety Datalink, 1996-2006.

And not surprisingly, several studies have shown that there isn’t any extra risk for Kawasaki disease after routine vaccines.

One even showed that getting vaccinated could be protective! Another benefit of vaccines and another reason you shouldn’t skip or delay your child’s immunizations.

What to Know About Vaccines and Kawasaki Disease

While anti-vaccine folks often list Kawasaki disease among their vaccine-induced diseases, several studies have shown that vaccines are not associated with Kawasaki disease, except to maybe have a protective effective if you are fully vaccinated.

More on Vaccines and Kawasaki Disease

Vaccines and Sudden Unexplained Death in Children

Can a child be fine one day and then die the next?

Tragically, they can.

There is even a name for it – sudden unexplained death in childhood.

Sudden Death in Children

Although 10% of deaths in children over age 12 months are classified as sudden death, most have explanations, such as asthma, epilepsy, or a heart problem (congenital malformations and arrhythmias). Unfortunately, some of these conditions, especially some infections and heart problems, aren’t discovered until after the child dies.

“Most sudden cardiac deaths that remain unexplained after necropsy are probably caused by primary cardiac arrhythmias.”

Sudden death in children and adolescents

About 16% of these sudden deaths don’t have any explanation though.

Surprisingly, these types of sudden, unexplained deaths are the 5th leading cause of death in children between the ages of 1 and 4 years. That adds up to about 400 deaths a year in the United States alone!

Vaccines and Sudden Unexplained Death in Children

Have you guessed the connection with vaccines?

If up to 16% of children who die suddenly don’t have a good explanation for why they died, then that leaves some to blame vaccines, often with a little help with myths and misinformation from anti-vaccine folks.

“…making general assumptions and drawing conclusions about vaccinations causing deaths based on spontaneous reports to VAERS – some of which might be anecdotal or second-hand – or from case reports in the media, is not a scientifically valid practice.”

Miller et al on Deaths following vaccination: What does the evidence show?

That’s despite the fact that both our safety monitoring systems and other studies have shown that vaccines are not associated with sudden unexplained deaths. In fact, deaths after vaccines are very rare.

“As for vaccines causing death, again so few deaths can plausibly be attributed to vaccines that it is hard to assess the risk statistically.”

WHO on Six common misconceptions about immunization

Studies have even shown a protective effect of getting vaccinated against SIDS.

“At the present time there is not enough known about the underlying mechanisms of death in SUDC to allow prediction of which children might die suddenly and unexpectedly. Additionally, there is no way to prevent SUDC since its cause is unknown. Through research, we strive to discover the risk factors and underlying causes of SUDC that will lead to its prevention. In the meantime, optimal pediatric care recommendations, including attending well child visits, maintaining current vaccinations, and obtaining appropriate health care when clinically indicated, should be followed.”

SUDC Foundation on Frequently Asked Questions

And it’s not just SIDS. We also see a “healthy vaccinee effect” in older kids, who have lower mortality rates than the general population, which includes some folks who aren’t vaccinated.

We don’t know what causes sudden unexplained death in children, although with continued research we hopefully soon will, and can then learn to prevent them. Until then, parents should feel confident that it is not caused by the vaccines, which are safe and necessary and work to protect them from many life-threatening vaccine-preventable diseases.

What to Know About Vaccines and Sudden Unexplained Death in Children

Vaccines are not associated with sudden unexplained death in children.

More on Vaccines and Sudden Unexplained Death in Children

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