Serious side effects of vaccines are rare. What does that mean?

The Pediatric Insider

© 2014 Roy Benaroch, MD

Since every second of my life, and then some, seems preoccupied with the transition to the New and Improved ICD-10 code set — I can’t imagine how I lived so long without being able to code for macaw attacks – I’ve had no time to write anything new. So today you get a refurbished, classic post. And by classic, I mean old. I put a new photo somewhere in the text to freshen it up, so I promise it’s worth a read. Enjoy!

“Serious side effects of vaccines are rare.”

Vaccines are not 100% safe. Like any medical intervention, there’s some risk (honestly, like anything at all, anything we do, there’s some risk. But let’s not get sidetracked here.) Side effects, including serious side effects, can happen after vaccines. What are these reactions, really? How often do they occur?

Here, I’m only talking about genuine, established side effects. Things are genuinely, scientifically, reliably linked to vaccines. Some things that had once been thought be a potential side effect of vaccines are now known to have been caused by other conditions (like seizures and encephalopathy after DTP, now known to be most-often caused by a rare genetic condition called Dravet Syndrome, that would have occurred whether the child was immunized or not.) There are also side effects reported that are clearly unrelated, like choking on a bean in the trachea or turning into the Incredible Hulk. We’ll ignore those, and concentrate on the real, serious, potentially deadly side effects that have been documented to be caused by vaccines. I’m going to list all of them, for every vaccine.

Any vaccine – Serious allergic reactions can occur. These do happen, though the rate of serious reactions depends on the vaccine. For most immunizations, the rate is less than 1 in 1 million; however, some very-rarely used vaccines can have a higher rate. The yellow fever vaccine, for instance, causes severe allergic reactions in about 1 in 55,000 people; anthrax vaccine is estimated to cause severe reactions in 1 in 100,000. Almost all severe allergic reactions occur within minutes of vaccination, and health care facilities who give vaccines should have people trained to treat rare reactions like these.

Influenza – The Pandemrix brand of influenza vaccine, which was never licensed or used in the United States, has been linked as a cause of narcolepsy in about 1 in 55,000 vaccine recipients in several countries in Europe. This product was only used during the 2009-2010 season. The CDC is currently sponsoring an international study to try to better understand this, and why that one formulation seemed to be a unique trigger for this rare condition.

In 1976, a different specific Swine Flu vaccine was linked to about 450 cases of Guillian-Barre Syndrome (GBS), a neurologic disorder that was estimated to occur in about 1 in 100,000 people who got that specific vaccine that year. The baseline rate of GBS is probably 1-2 per 100,000, so when 45 million doses of vaccine were given in 1976, some cases were going to occur coincidentally. Substantial studies have shown that other flu vaccines from more-recent years do not cause GBS. Ironically, influenza disease itself causes more GBS than even the 1976 Swine Flu vaccine is purported to have caused, and even if that association were true influenza vaccination would prevent far more GBS than it would trigger.

Japanese encephalitis – Rarely used in the United States, the Japanese Encephalitis vaccine has been linked to prolonged arm and shoulder pain among vaccine recipients. I could not find an exact rate, but this appears to be an uncommon reaction.

MMR — About 1 in 30,000 people given a dose of MMR will have a drop in their platelet count, which can predispose to bleeding. The rate of low platelets is much higher in real measles than after the vaccine, so, again, ironically MMR probably prevents more cases of low platelets than causes it. This condition is temporary and almost always requires no treatment at all.

Polio — The oral polio vaccine, no longer used in the United States, could trigger genuine, full-blown polio in some people—probably about 8 per year in the entire US, back when we used the oral version. We’ve been using only the injected polio since the mid-1990s, which carries zero risk of causing polio.

Rotavirus – Rotavirus vaccines carry a small risk of causing an intestinal blockage called “intussusception.” This condition is treatable, though it often requires a brief hospitalization. The risk was highest after the first doses of the original brand of vaccine, Rotashield, which was withdrawn from the market; the risk after current brands is probably in the range of 1-3 in 100,000. However, rotavirus itself, the real infection, is also a cause of intussusception. To put this in perspective: using the high end of the risk estimates, about 40-120 vaccinated infants may develop intussusception each year in the USA, compared to 65,000 infants who had been hospitalized for rotavirus illness each year prior to the vaccine becoming available.

Smallpox – Routine smallpox vaccinations stopped by 1970 in the US, but a smallpox vaccine is available for high-risk researchers and military people and others thought to be at risk of exposure. The vaccine can cause heart problems in 1 in 175 people, and there is a risk that the vaccine virus can spread on the skin of a vaccinated person or contacts, especially when the skin is damaged or there are immune problems.

Yellow fever – Used only in certain travelers, some kinds of typhoid vaccine can causes severe neurologic problems (about 1 in 125,000) or death, especially in elderly people (1 in 500,000).

That’s it—that’s the list. All of the serious, lasting, you-need-to-worry about side effects. You’ll notice that almost all of the really serious side effects occur only with vaccines that aren’t likely to be recommended for your children. Most of the routine childhood vaccines (DTaP, HIB, pneumococcal conjugate, hepatitis B, hepatitis A, chicken pox, meningococcal conjugate, human papilloma virus) only carry a very rare risk of allergic reactions, and even those are entirely treatable and temporary. In other words, science has failed to find any evidence for any real, lasting, serious vaccine reactions among any of the vaccines currently recommended for routine use in children in the United States.

When we say “serious side effects are rare,” we mean “serious side effects are very very very rare.”

This is an orcaWhat parents need to worry about are diseases, not vaccines. Don’t let the scaremongers and internet rumors sway you. The risk of a serious, lasting side effect from any routine childhood vaccine is just about zero. Make sure your children are safe and protected. Vaccinate!

Explore posts in the same categories: Medical problems

3 Comments on “Serious side effects of vaccines are rare. What does that mean?”

  1. wzrd1 Says:

    Well, the most “hazardous” vaccine ever was indeed the smallpox vaccine. Considering the morbidity and mortality rate of smallpox, even a 1% chance of death was trivial compared to the 33 – 35% morbidity and mortality rate from the disease itself.
    I still received the vaccine repeatedly, Army stuff.

    As for intussusception, there are always idiopathic cases, totally unlinked to the vaccine. To see that present in one variant of vaccine is indeed troubling. The damage required to trigger intussusception is highly specific, specific nerves connective tissue or muscles have to cease function in order for a section of intestine to telescope inside of another.
    That’s worthy research regardless of the theorized cause.

    As for ICD-10, it offers a granularity never found before, for it may very well be a public health concern if macaw attacks trend upward.

    OK, snark aside, whoever dreamed up ICD-10 is either the worst case ever in human history OCD sufferer or an actuarial, which really is essentially the same disease. 😉
    But then, that’s what software is for, isn’t it?
    Sort through 16000 potential combined codes for 14400 diseases actually does require more processing power than the meat on top of our shoulders can provide.
    But then, if a handful of people were suddenly attacked by a Macaw and contracted MERS-CoV infection, that would be of import to public health officials.
    I estimate that probability of being one of three, slim chance, fat chance and no chance.
    See the actuarial bit for a more likely reason.
    After all, incorrectly code under any ICD version would result in payment being held up or simply denied.

    BTW, as you’re boning up on ICD-10, what *is* the ICD-10 code for prion disease contracted from a Martian tick bite in Martian fall?
    Somehow, I suspect there would indeed be a code and sub-code.


  2. My mother got GBS from the H1N1 vaccine in 2010; the fact that this is rare doesn’t impress me, since it’s ruined my life 100%. “Rare” just means that most OTHER people who got the vaccine got to move on with their lives, while I’m stuck as a caretaker.

    However, I still got my baby vaccinated according to standard schedule. It boils down to this: would I feel less guilty if my baby suffered from a vaccine side effect or from the disease itself? I’d have to conclude that I’d sleep better at night if my baby got the vaccine side effect instead of the disease. Of course the chances of that are much lower (again, if it hits your kid then it affects you 100%), so it depends on what kind of guilt you want to feel.

    Anyway, thanks for this blog post. I’ll carry on with getting my 9-month old his shots. In the past, I’ve had all my travel vaccinations–including the yellow fever–without a second thought.


  3. wzrd1 Says:

    That reminds me, I’m out of date on a few of my vaccinations. As soon as the medical coverage kicks in, something else for doctor to do.
    Boy, but doctor’s going to be busy with this new patient and his wife!


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: