Vaccinations Archive

Research we're watching

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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.

Ask the doctors

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Q. I've read that getting the flu shot annually will weaken my immune system over time. Is this true?

A. A study published in the March 1, 2017, issue of The Journal of Infectious Diseases investigated whether getting an annual vaccination against influenza (flu) can weaken your body's natural ability to protect itself from the disease. Past studies have raised similar concerns. Researchers at the University of Bergen in Norway followed 250 health care workers. Some of them got a flu vaccination every year from 2009 through 2013. The others only received the vaccine once in 2009 and not in the years from 2010 to 2013. The researchers then took blood samples before the influenza season (and before people were vaccinated that season), from the members of both groups and looked at different markers to gauge how well their immune systems would respond to the influenza virus. They found that getting an annual flu vaccination did not weaken the immune system. As a group, the people who got the flu shot annually appeared to have a better immune response to influenza than those vaccinated only once.

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.