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 / Updated  / Source: TODAY
By A. Pawlowski

With doctors and patients on high alert for symptoms after last year's deadly flu season, cases of what appear to be unusual signs of the disease have been getting lots of attention.

The beginning of December marks National Influenza Vaccination Week, designed as a reminder it's not too late to get a flu shot during the holidays and beyond. Just 37 percent of Americans got vaccinated last season, the Centers for Disease Control and Prevention reported, a major reason for the nearly 80,000 flu deaths last year.

You're already on the lookout for fever, cough, sore throat and fatigue, but could hives signal the flu? Many people became alarmed after a Nebraska woman’s Facebook post about her son’s experience went viral in January.

The boy tested positive for influenza, but had no symptoms other than the hives. "No fever, no cough, and no runny nose," Brodi Willard wrote in her post, which included a photo of the boy holding up an arm covered in bumps.

Are hives a symptom of the flu?

But while a rash with a fever is an emergency flu warning sign for children, hives just by themselves aren’t necessarily something to be on the lookout for, an infectious disease specialist said.

Dr. William Schaffner, a professor of preventive medicine at the Vanderbilt University School of Medicine, called the case "very, very odd," especially since the boy had no other symptoms. He shared the details with other colleagues who are flu experts.

“We’re all scratching our heads. We’ve never heard of it before, so I think the answer is a strong maybe. It certainly is unusual,” Schaffner told TODAY. “Just a rash alone without any other symptoms… I wouldn’t run right away with a diagnosis of influenza on the basis of this anecdote.”

He wondered if the child was carrying the influenza virus without being infected, with the hives just a coincidence.

“If you go out and test a lot of children without symptoms, you will find that (some) are carrying a respiratory virus, whether it’s influenza or RSV or adenovirus or rhinovirus, but they’re not sick. Children can do that. So one of the questions would be: Is this just a coincidence? It’s certainly not in the text books,” Schaffner said.

He advised parents who see their child develop the hives to focus on treating the skin condition since most children get such rashes and they get better very quickly. “I don’t think that they should get worried” about the flu, he added.

But if your child starts accumulating other symptoms, like a fever, sore throat, runny nose, malaise, vomiting and diarrhea, then he or she may indeed be sick with the flu.

Serious flu symptoms that warrant a trip to the emergency room:

The CDC lists the following serious flu warning signs.

Serious flu symptoms in children:

  • Fast breathing or trouble breathing
  • Bluish skin color
  • Not drinking enough fluids
  • Not waking up or not interacting
  • Being so irritable that the child does not want to be held
  • Flu-like symptoms improve, but then return with fever and worse cough
  • Fever with a rash

Serious flu symptoms in adults:

  • Difficulty breathing or shortness of breath
  • Pain or pressure in the chest or abdomen
  • Sudden dizziness
  • Confusion
  • Severe or persistent vomiting
  • Flu-like symptoms that improve but then return with fever and worse cough

A special risk for older people

Middle-aged and older adults should be aware that they face an increased risk of a heart attack and stroke for a few weeks after they recover from the flu, Schaffner said. It happens because the virus infection provokes an inflammatory response in the body, which continues for a while before it completely goes away. This inflammatory response can involve blood vessels to the heart and brain, and cause them to close off, recent research shows. It’s a risk the average person and most doctors still don’t know about, Schaffner added, and another good reason to get the flu vaccine.

“Every case of flu you can prevent also keeps your risk of heart attack and stroke lower,” he said.

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