• By Deborah Balzer

Infectious Diseases A–Z: Facts on vaccine safety and side effects

July 15, 2019
a small child being prepared to get a vaccine shot

A resurgence in measles infections in the U.S., Europe and other locations may be a result of increased vaccine hesitancy over safety concerns. Dr. Gregory Poland, director of the Mayo Clinic Vaccine Research Group, wants to assure parents that possible side effects from vaccines are rare.

"When we talk about the safety of a vaccine, we're talking about — in terms of adverse events — transient, low-level, spontaneously resolving side effects like a sore arm, a low-grade fever or being achy," says Dr. Poland. "The chance of a serious vaccine-related side effect is very rare. The most common side effect would be anaphylaxis, which happen in about 1 in 1 million vaccinations. In contrast, the risk of dying if you get measles is 1 to 3 out of 1,000."

There have been 1,095 known and reported cases of measles infections in the U.S. from Jan. 1 to July 3, according to the Centers for Disease Control and Prevention. It's the highest number of measles cases in the U.S. since 1992.

Watch: Dr. Gregory Poland explains vaccine safety.

Journalists: Broadcast-quality sound bites with Dr. Gregory Poland are in the downloads at the end of the post. Please "Courtesy: Mayo Clinic News Network."

Parents' reluctance to vaccinate their child may be linked to misinformation about the safety of a vaccine. "Most people are just concerned about their health and they want to do the right thing. But they're misinformed. They are listening to celebrities with no scientific training or listening to their next-door neighbor who's telling them about anecdote, or they have unusual ways of cognitively processing information," says Dr. Poland. 

"Vaccines should be held to a very high standard of safety, and they are," says Dr. Poland. "When you go into medical records and you actually look at millions of patients, serious side effects are so rare. We can't do the kinds of genetic studies, for example, that we would like to do. There are just not enough, fortunately, but we can't study it."

Measles is an extremely contagious illness spread by respiratory droplets. Common complications from measles infection may include ear infection, pneumonia and encephalitis, the latter of which can result in permanent brain damage. The disease can be prevented with the measles, mumps and rubella,or (MMR) vaccine.

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