Vaccines and immunizations Archive

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Q. There has been a lot of talk about the severity of this flu season, and I recently heard that influenza also can trigger a heart attack. Should I worry?

A. Influenza is responsible for about 10,000 to 20,000 annual deaths, mostly from pneumonia or internal organ failure. In other situations, influenza infection strains a person's health, which can worsen underlying conditions, such as heart disease.

Research we're watching

 Image: © grinvalds/Getty Images

If you have an egg allergy, you may have been told not to get a flu shot. That's because the vaccine is grown in eggs and may contain a small amount of egg protein, which — it was feared — could trigger an allergic reaction. But a new guideline from the American College of Allergy, Asthma and Immunology (ACAAI) dispenses with that old advice and says even people with an egg allergy should roll up their sleeves and get the shot to protect themselves from the flu.

"When people get flu shots, health care providers often ask if they are allergic to eggs," allergist Dr. Matthew Greenhawt, chair of the ACAAI Food Allergy Committee and lead author of the practice parameter, said in a written release. "We want health care providers and people with egg allergy to know there is no need to ask this question anymore, and no need to take any special precautions. The overwhelming evidence since 2011 has shown that a flu shot poses no greater risk to those with egg allergy than those without." Numerous studies have found that patients with egg allergy — even those with life-threatening allergies to egg — have gotten the shot and did not suffer any ill effects. This suggests there isn't enough egg protein in the vaccine to cause a reaction.

Research we're watching

Not only is obesity a risk factor for flu complications, but it might actually make the flu vaccine less effective, says a study published online June 6, 2017, by the International Journal of Obesity. Scientists at the University of North Carolina at Chapel Hill found that the flu shot provides less protection in people who are obese.

The study compared flu rates in 1,022 people during two recent flu seasons. All participants were vaccinated against the flu. The researchers looked at immune response to the vaccine and also tracked who went on to get the virus. They found that nearly 10% of obese participants got the flu, compared with 5% of their healthy-weight counterparts. This is bad news, because individuals with a body mass index of 40 or higher are also more prone to flu complications.