• Infectious Diseases A–Z: What are the risks of vaccination?

All vaccines come with a risk of side effects. With that knowledge, Dr. Gregory Poland, director of the Mayo Clinic Vaccine Research Group says, "We have to be very careful in discerning what's a true vaccine reaction and what isn't, and balance that against the benefit versus the risk — just like we do with the rest of life."

Defining a vaccine reaction is important, says Dr. Poland. "If we look at something like a sore arm or a little redness, that might be 50% – 70 % of us. Those are transient. They go away and don't require any treatment. When most people talk about a serious vaccine complication, probably the most common would be an anaphylactic reaction — an allergic reaction. That happens about one in a million doses administered."

Watch: Dr. Gregory Poland discusses 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."

Serious complications from vaccines are rare. "We can't put together enough people who have had severe reactions to vaccines that have harmed their health or damaged them in some way to actually study it. They are that rare," says Dr. Poland. "Another way of saying that vaccines are that safe."

Some perceived reactions to vaccines are actually just temporal associations, according to Dr. Poland. "Let me give you two lines of evidence for that. One is where studies have been done where somebody is told they're going to get, let's say, a flu vaccine because they say, 'The flu vaccine causes the flu in me.' And they get a salt water placebo. No difference in reaction rates. I did one of those studies myself and published it. Three hundred people that we tested and found no difference in reaction rates."

That's not to say all vaccines are perfectly safe in all people. "Like any medicine, we have to know what vaccine is needed and whether the person receiving it has any contraindications to receiving it," says Dr. Poland. "That is the job of the physician to determine with the patient."

The bottom line, says Dr. Poland, is that vaccines are safe and save lives.

Related articles