Screening for Vaccine Reactions

Vaccine Basics

A baby visiting her pediatrician.
Some simple screening questions can help identify kids at increased risk for vaccine reactions because of medical contraindications.. Photo by Getty Images

Worry over vaccine reactions is what leads some parents to needlessly skip or delay some of their kid's vaccines. Unfortunately, that doesn't lead to fewer reactions, it just leaves those kids unprotected and at risk for more vaccine-preventable diseases.

In addition to understanding many of the myths and misinformation that surround vaccines and scare parents away from vaccinating their kids, understanding the things that might put kids at increased risk for reactions can help you make the decision to get your kids fully vaccinated.

Is Your Child at Risk for a Vaccine Reaction?

To help figure out if your child has any contraindications or precautions to getting vaccines, experts recommend that parents answer some basic questions before their kids get any vaccines, including:

  • Is your child sick today? - a mild illness, even if your child is taking antibiotics, is not usually a reason to delay getting a vaccine.
  • Does your child have allergies to medications, food, or any vaccine? - this question can help to identify severe allergic reactions to specific vaccines or vaccine components, including latex, yeast, gelatin, eggs, neomycin, polymyxin B, or streptomycin, etc., although you should keep in mind that severe allergies that would affect your child getting vaccines are very rare
  • Has your child had a serious reaction to a vaccine in the past? - if truly related to the vaccine, that would likely be a reason to avoid it in the future
  • Has your child had a seizure, brain or nerve problem? - in general, if your infant has a progressive neurologic disorder (one that is getting worse), then the DTaP vaccine would likely be deferred until your child's condition stabilized
  • Has your child had a health problem with asthma, lung disease, heart disease, kidney disease, metabolic disease such as diabetes, or a blood disorder? - this is to identify kids who shouldn't get the live nasal spray flu vaccine and who should get a flu shot instead
  • Does your child have cancer, leukemia, AIDS, or any other immune system problem? - some children with immune system problems should not receive live virus vaccines
  • Has your child taken cortisone, prednisone, other steroids, or anticancer drugs, or had radiation treatments in the past 3 months? - Some children taking medicines that can alter their immune system should delay getting live virus vaccines. Keep in mind that a short course of steroids, such is used to treat asthma or poison ivy, would not typically be a reason to delay getting a vaccine.
  • Has your child received a transfusion of blood or blood products, or been given a medicine called immune globulin in the past year? - this can be a reason to delay getting a live virus vaccine
  • Is your teen pregnant or is there a chance she could become pregnant during the next month? - then shouldn't get a live virus vaccine
  • Has the child received vaccinations in the past 4 weeks? - if not given at the same time, live virus vaccines shouldn't be given within 4 weeks of each other

    If you think that your child is at risk for a vaccine reaction or has had a vaccine injury, be sure to talk to your pediatrician. You should also report any vaccine reaction to Vaccine Adverse Event Reporting System (VAERS).

    Keep in mind the MTHFR genetic testing is not something that will help you determine if your child is at risk for a vaccine reaction. The MTHFR vaccine issue and online testing for MTHFR gene mutations is just the latest thing that is scaring parents from vaccinating their kids. That's not to say that MTHFR gene mutations aren't important. Homocystinuria is tested for as part of most baby's newborn screen and it can be caused by a MTHFR gene mutation. There are many MHTFR mutations though, with some being found in as many as 26% or more of the population, and some may even have protective effects against cancer. They won't tell you if your child is at risk for a vaccine reaction though.

    Getting Evaluated for a Vaccine Reaction or Injury

    Fortunately, true vaccine injuries are very rare. For example, while SIDS, early symptoms of autism, and other things may seem to correlate with getting vaccines, it has been proven (again and again and again) that they are not caused by vaccines.

    We also know that vaccines don't cause or put kids at risk for celiac disease, multiple sclerosis, type 1 diabetes mellitus, chronic arthritis, or any type of allergic disease, including allergies, asthma, or eczema.

    More often, coincidental events get blamed on vaccines and parents might seek a vaccine exemption.

    It is much more important to carefully evaluate the situation and determine if it really was a vaccine reaction. Your pediatrician might even use the Clinical Immunization Safety Assessment (CISA) algorithm tool to help determine if your child's reaction is consistent with being caused by a vaccine.

    There is also an algorithm to help determine if a child had an allergic reaction to a vaccine. If a allergic reaction is suspected and the child is still not immune (needs additional doses of vaccine), then skin testing might be a good option before a parent seeks a medical exemption.

    Whether it was an severe allergic reaction (anaphylaxis) or other reaction, to help figure out if it was associated with getting a vaccine, it is important to know:

    • when the symptoms first started, especially in relation to when your child got his last vaccines
    • all of the symptoms your child developed
    • if anything else have caused the symptoms
    • which vaccines your child received
    • if your child ever had any previous reactions to any vaccines

    If you are still not sure if your child had a vaccine reaction, your pediatrician can request a Clinical Immunization Safety Assessment evaluation at the CDC for extra advice.

    Again, you should also report any vaccine reaction to Vaccine Adverse Event Reporting System (VAERS).


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    Centers for Disease Control and Prevention. Conditions Commonly Misperceived as Contraindications to Vaccination. Updated: July 17, 2012. Accessed July 2015.

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    Myléus, Anna, PhD, MD, Early Vaccinations Are Not Risk Factors for Celiac Disease, Pediatrics. 2012 Jul;130(1):e63-70.

    Offit, PA. Addressing parents' concerns: do vaccines cause allergic or autoimmune diseases? Pediatrics. 2003 Mar;111(3):653-9.

    Rosenberg, Nurit. The Frequent 5,10-Methylenetetrahydrofolate Reductase C677T Polymorphism Is Associated with a Common Haplotype in Whites, Japanese, and Africans. American Journal of Human Genetics. Volume 70, Issue 3, March 2002, Pages 758–762

    Vaccines (Sixth Edition) 2013

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