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Paul A. Offit, MD, talks about potential allergens in vaccines.
Paul Offit, MD: Hi, my name’s Paul Offit. I’m talking to you today from the Vaccine Education Center here at The Children’s Hospital of Philadelphia. A parent can reasonably ask the question, “Is there anything in a vaccine to which my child could be allergic? I have a highly allergic child, is there anything in a vaccine that I should worry about?”
And actually there are two things in vaccines that are potential allergens. The first, and probably the one which we have the most experience, is egg proteins. There are a couple of vaccines: the yellow fever vaccine, which obviously is not routinely recommended for children, but the flu vaccine, the influenza vaccine, is made by growing the virus in eggs, and then taking the virus, purifying it, and then inactivating it with a chemical.
So, there can be residual amounts of egg protein in the influenza vaccine. So if you have a child with severe egg allergies, is it possible then that the influenza vaccine could cause a severe allergic reaction? One characterized by hives, or difficulty breathing, or worse, low blood pressure and shock.
Now, in the past that was true. That people who were severely allergic to eggs could have a severe allergic response to the egg proteins contained in influenza vaccine. These days the quantity of contaminating ovalbumin, or egg proteins, in vaccines is so low that even the children with severe egg allergies can get those vaccines safely. So that’s not an issue anymore.
The second thing that is an issue, and probably the most common allergen in vaccines, is something called gelatin. It’s used as a stabilizing agent for a couple vaccines, the chickenpox vaccine is one example. Now, the kind of gelatin that’s used is porcine gelatin, meaning it’s actually obtained from pigs.
Gelatin is actually commonly used in foods. JELL-O probably being the best example. But all the gelatin that’s used in food is bovine gelatin, meaning derived from cows. So you can actually not have an allergic response to bovine gelatin, but still have an allergic response to the porcine gelatin.
So how to avoid all this? How do you know? Sometimes the only way that you know whether a child is allergic to a vaccine component is when they get the vaccine. Which is why doctors, and nurses, and nurse practitioners ask parents to stay around for about 15 or 20 minutes after the child has gotten a vaccine to make sure they don’t have an allergic reaction.
Because when they have an allergic reaction to either gelatin or to egg proteins, it’s immediate. In fact that’s what it’s called, it’s called an immediate, or type 1 hypersensitivity reaction. If that happens, then the doctors have things like epinephrine in the office to be able to immediately treat that hypersensitivity reaction. So basically, you jump with a net by making sure that you stay in the doctor’s office for 15 to 20 minutes after getting a vaccine.
Related Centers and Programs:
Vaccine Education Center
Last Reviewed on
Jul 18, 2016