The life-threatening dangers of long flu — from diabetes risk to brain inflammation

It’s the start of another flu season in the U.S. and millions of Americans are expected to fall ill.

Most cases end on their own after a few days but, in rare cases, symptoms can last for months — similarly to long Covid infections that are estimated to affect one in six people.

People can experience a persistent cough, fever and runny nose, as well as inflammation that negatively affects organs, including the brain. There are also mental health problems, such as memory problems and sleepiness.

These illnesses are what experts call “long flu,” impacting the respiratory system, according to researchers at WashU Medicine.

“Long Covid is much more of a health problem than Covid, and long flu is much more of a health problem than the flu,” Dr. Ziyad Al-Aly, a clinical epidemiologist at Washington University, explained in a 2023 statement.

Al-Aly and his colleagues analyzed the medical records of more than 10,000 people hospitalized for flu and 80,000 who were hospitalized for Covid, finding that problems were still reported up to 18 months after their infection.

Long flu was associated with a higher risk of chest pain, rapid heart rate, cough, shortness of breath, low blood oxygen and Type 1 diabetes.

It’s suspected that around 3-5 percent of people who get the flu may develop long-term symptoms given this data, he told The Washington Post Tuesday. However, the actual number remains unclear.

Thankfully, getting a flu shot provides the protection to fight the flu, including both short- and long-term infections.

The flu shot has been linked to a reduced risk of Alzheimer’s disease and lower risks for severe cardiovascular events.

And newly available mRNA flu shots provide even more protection, medical researchers say.

But the number of people getting vaccinated has fallen in recent years, despite widening availability.

“The flu causes a tremendous number of hospitalizations, and every year, millions of people are symptomatic with the flu, yet still, people are not getting vaccinated,” Dr. Stephen Thacker, a pediatric infectious diseases specialist with MUSC Health, said in a release.

Doctors say now is the time to get shots this season.

“I usually advise my patients to get their flu shot between Halloween and Thanksgiving. Since its protection usually lasts about six months, you don’t want to get it too early and have it wear off before the end of flu season,” Dr. Keith Roach, an internist and associate attending physician at NewYork-Presbyterian/Weill Cornell Medical Center, said in a statement.

The end of flu season can extend into April or even May, he noted. That’s why it’s never too late to get a flu shot, either.

Infections haven’t picked up nationally yet, but emergency department visits are on an upswing a little early in the West, according to the latest federal data.

This is also unusual in that flu activity typically starts in the Southeast and then spreads across the U.S.

Flu results in between 9.4-51 million illnesses a year and some 6,300-52,000 deaths, according to the Centers for Disease Control and Prevention.