Allergies to vaccines are extremely rare and even when they do occur, allergists can safely administer vaccines, Canadian experts report.
Immunoglobulin E (IgE) allergies that cause hives, swelling, wheezing or anaphylaxis occur in only 1 of 760,000 vaccinations.
Such a reaction typically starts within minutes of a shot, is unlikely to occur after 60 minutes, and is highly unlikely after four hours, according to two physicians at McMaster University in Hamilton, Ontario.
Fever, local pain and swelling can occur up to 21 days after a vaccination and are not signs of allergy, according to Dr. Derek Chu, a fellow in clinical immunology and allergy, and Dr. Zainab Abdurrahman, an assistant clinical professor in pediatrics.
Other than the yellow fever vaccine, an egg allergy is no reason to avoid vaccinations, they said.
No special precaution is needed when people with an egg allergy get a shot for flu; measles, mumps and rubella; or rabies -- even though those vaccines may contain a tiny amount of egg protein, the Public Health Agency of Canada and the Canadian Pediatric Society said.
A reaction after a vaccination could be due to a latex allergy triggered by the rubber stopper or preloaded syringe, and not the actual vaccine.
If you actually have a vaccine allergy, an allergist can give you the vaccine a bit at a time, the doctors said.
The paper was published April 8 in the Canadian Medical Association Journal.
The U.S. Department of Health and Human Services has more on vaccines.