While getting your baby her first shots isn’t particularly pleasant, immunizations can be life-saving. And if you’re at all nervous about your little one having a reaction, a new study in the journal Pediatrics should ease your worries: It found that the risk of a severe adverse reaction to a vaccine is extremely low, even among kids who’ve already had one.
What the Study Looked At
Canadian researchers looked at 29 studies published between 1982 and 2016, each of which had at least five participants, most of whom were children. All participants already had an adverse reaction to a vaccine, including fever, limb swelling, seizures, pain, apnea, decreased appetite, persistent crying, drowsiness, vomiting or other rare conditions. Allergic reactions included pink eye, facial swelling, chest tightness and cold-like symptoms such as a cough, sore throat and hoarseness. The most-studied vaccines were DTaP, influenza, HPV, diphtheria-tetanus and meningococcal B vaccine.
What It Found
Less than 1 percent of people who had a serious reaction to a vaccine — including anaphylaxis (a severe allergic reaction), seizures or apnea in infants — had a recurrence the next time they got vaccinated. In seven out of eight studies, the odds of another allergic reaction to a vaccine were low. And none of the 727 participants who had an allergic reaction or anaphylaxis had anaphylaxis when they were re-immunized.
For minor or moderate reactions, such as fever, swelling, allergic reaction, sleepiness, thrombocytopenia (low blood platelet count, which can sometimes result in abnormal bleeding), decreased appetite, vomiting or persistent crying, the risk of recurrence was between 4 percent and to 48 percent — and symptoms were usually similar or less severe the following round.
About half of all children who experienced extensive limb swelling (ELS) after the fourth DTaP dose and a third who had pain at the injection site following any DTaP shot had a reaction at the next dose, and all recovered completely. Fever was another of the most common recurring side effect with the DTaP and flu vaccines, although none of the fevers were severe. Vomiting, persistent crying, decreased appetite and drowsiness recurred in 15 percent, 24 percent, 25 percent and 35 percent of re-vaccinated people.
“People think that if you develop any kind of rash or cough after a vaccine, you are allergic to that vaccine,” study author Gaston de Serres told Consumer Reports. “Our research shows that that is not the case. Most of these events are one-off. They’re transient, they don’t recur, and they don’t cause permanent damage — especially compared with the diseases against which we are trying to immunize.”
What This Means for You
If you’re anxious about getting your little one immunized, this study should come as a relief: Severe adverse reactions to vaccines are extremely rare, even among kids who already had a reaction. And if your child already had a reaction to a vaccine, reoccurrence is unlikely; by taking a few precautions, getting the next dose is safe.
As the Centers for Disease Control and Prevention (CDC) notes, most reactions to vaccines are mild (like redness and swelling where the shot was given) and go away within a few days. Keep in mind, the diseases vaccines help prevent can be devastating and even life-threatening. Still got questions or concerns? Check in with your child’s doctor, who can talk through specific concerns with you. But overall, the benefits of vaccines far outweigh the risks.