The Actual Risks of Vaccines (It Turns Out There Aren’t Many)

This article was originally published on the Huffington Post on July 8, 2014.


These days, we hear a lot about the risks of vaccines. As a pediatrician, I talk to many parents who are very frightened about those risks — and some choose not to vaccinate because of their fear.

Some of the risks we hear about are real, but some of them aren’t.

I absolutely support the right of every parent to make what they feel is the best decision for their child. The vaccination decision, however, isn’t a purely personal one. When people don’t immunize, it can lead to more cases of vaccine-preventable diseases — many of which can be deadly, especially for the young, the old and those with health problems.

And when people make the decision not to vaccinate based on misinformation, well, that makes it so much worse.

No medical treatment is 100 percent safe for all people. Heck, nothing in this world is 100 percent safe for all people. Crossing the street, eating a piece of hard candy, riding in a car and swimming have all been known to turn out badly — and yet those aren’t controversial.

I know, getting vaccines is different than riding in a car. There are lots of reasons, but one is that vaccines feel, well, more optional than riding in a car. Also, the risks of riding in cars are clear and well-known, and we know what we can do to prevent them (like using a car seat, and driving carefully). But the risks of vaccines seem a whole lot murkier.

That’s why the recent report about the actual risks of vaccines is so helpful. Researchers looked at hundreds of studies about vaccines and used statistics to figure out the most common “adverse effects.” These are the risks we need to really think about, as opposed to the mild fever and muscle soreness that goes away quickly, or the one-in-a-million risks that nobody can predict.

While it’s certainly good to know what the one-in-a-million risks are, if you are going to truly worry about those you should pack your child in a bubble right now — because the risks of playdates, playgrounds, going to school and taking most medications (as well as eating most foods) are higher. In saying that, I don’t mean to sound disrespectful of parents who worry about the rare risks of vaccines. It’s just that as a doctor, it’s frustrating to me when people only look at vaccines that way, vaccines that could keep their child and others from getting sick, and don’t pick apart the risks of everything else in their child’s life. And the illnesses vaccines prevent have risks that are much higher than one in a million, an important point that often gets lost.

Here are the risks that researchers found:

  • MMR vaccine: febrile seizures (while scary, these don’t cause long-term effects), and severe reactions in those who are allergic to the vaccine.
  • Hepatitis B vaccine: allergic reactions in people who are “yeast-sensitive” (people should check with their doctors to see if it applies to them)
  • Hepatitis A vaccine: can cause a bruising-type rash (purpura) although usually mild and short-lived.
  • Polio vaccine: the researchers found one study that showed an increase risk of food allergy in newborns who got the shot (they didn’t find it in older babies or children who got it), but only if they had eczema and a family history of food allergies.
  • Influenza vaccine: vomiting and diarrhea (for a brief period of time), febrile seizures
  • Pneumococcal vaccine (PCV13): can cause febrile seizures, especially if given with the flu shot.
  • Rotavirus: can cause intussception, a condition in which the intestine folds in on itself (while this can be dangerous, it can be fixed).
  • Meningococcal vaccine (Menactra): severe allergic reactions in people who are allergic to it.
  • Varicella (chicken pox) vaccine: can cause illness in children who have problems with their immune system (so they shouldn’t get it). It can also cause a much milder case of chicken pox in healthy children, and can cause purpura (that bruising rash again), usually mild and short-lived.

All of these are still rare — for example, intussception happens in between 1 and 5 out of every 100,000 children vaccinated. The risk of being allergic is very small too, which is good since it’s almost impossible to know about that risk ahead of time.

That’s it. They couldn’t find anything for the DTaP vaccine or the HIB vaccine. They couldn’t find any association with autism. And they couldn’t find any risk from giving a lot of vaccines at once; in fact, one study found that getting several vaccines may help protect children against leukemia.

Check out the report. Check out the Vaccine Adverse Event Reporting System, which is where information about events that happen after vaccines is kept. Ask your doctor every single question you have. We in the medical profession aren’t trying to keep anything secret, truly — and we rather desperately don’t want children or anyone to be hurt, either by the vaccines or by vaccine-preventable diseases.

Please, make your decisions based on the best information possible. There’s just too much riding on it.

Claire McCarthy, MD, is a pediatrician at Boston Children’s Hospital. An Assistant Professor of Pediatrics at Harvard Medical School, an official spokesperson for the American Academy of Pediatrics and a senior editor for Harvard Health Publications, she has been writing about health and parenting for magazines, newspapers, and the internet for more than 20 years. She and her husband are raising five children ranging in age from 23 to 8. She blogs for Thriving, the health and parenting blog of Children’s Hospital Boston, and for as MD Mama; you can follow her on Twitter at @drClaire.

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