The US is experiencing its highest number of flu hospitalizations in a decade, and there are no signs that the virus will peak or disappear in the coming weeks. With the busy holiday season approaching and a relatively low percentage of adults vaccinated against the flu, millions of people are at potential risk of serious complications.
While most people who get the flu recover within a few days, some may develop life-threatening complications. According to the latest data from the Centers for Disease Control and Prevention, there have been at least 7,300 flu deaths since October, including 21 children.
About 120,000 people have been hospitalized in recent months because of the flu, the CDC reported. Nine out of 10 adults hospitalized with the flu had at least one underlying medical condition.
People most at risk of serious illness from the flu include children under age 5, people over age 65, people with weakened immune systems, and people who are pregnant.
People with complications from the flu most often end up in the hospital because the virus progresses to pneumonia, said Dr. Peter Chin-Hong, professor of medicine and infectious disease physician at the University of California, San Francisco.
Bacterial pneumonia can develop when the flu virus spreads to the lower respiratory tract, leading to difficulty breathing that may require supplemental oxygen.
Warning signs of pneumonia
While many of the symptoms of the flu, such as fever and body aches, overlap with pneumonia, there are some clues that may indicate a more serious lung infection is on the way.
A cough with yellow or green sputum, increasing fever, and chest pain when breathing deeply or coughing are warning signs of pneumonia.
Some patients with pneumonia may also develop sepsis, a complication that can lead to organ failure and death, especially if not treated quickly.
Pneumonia from the flu isn’t limited to just older people, said Dr. Jonathan Grein, an infectious disease physician and hospital epidemiology director at Cedars-Sinai Medical Center in Los Angeles.
“Unfortunately, sometimes we also see young, healthy people with very severe pneumonia,” Grein said. “It can happen to anyone.”
Influenza and pneumonia together are the ninth leading cause of death in the U.S., killing tens of thousands each year, according to the CDC.
Influenza virus can increase the risk of a heart attack
A flu attack is also associated with an increased risk of heart attack, as are rare cases of inflammation in the brain or muscles.
“Flu can cause all these non-lung problems that people don’t usually think about,” Chin-Hong said.
A 2018 study found that patients were six times more likely to have a heart attack the week after a flu infection than at any time in the year before or the year after the infection.
Chin-Hong said he has treated people with flu who developed encephalitis — a dangerous inflammation of the brain that can be caused by viral infections — or myositis, which causes painful weakening of muscles.
Being sick with the flu can also exacerbate flare-ups of chronic diseases such as diabetes or asthma, Grein said.
“The flu triggers an immune response in your body to help fight off that infection, but sometimes that response can be a little overwhelming,” he said. “In a patient with diabetes, their blood sugars go up, or you can see patients with underlying lung disease, if they get infected with the flu, that can make their breathing difficult.”
Pregnant with flu
One of the most at-risk groups for flu complications is pregnant people, in part because of the weakening of the immune system during pregnancy, said Dr. Carlos del Rio, an infectious disease expert, an executive associate dean at Emory University School of Medicine and Grady. Health system in Atlanta.
Even for a healthy woman, changes in heart and lung functions during pregnancy can increase the chances of becoming seriously ill with the flu. Despite this, many patients remain unvaccinated during their pregnancy.
A recent CDC study found that only half of all pregnant women received their flu vaccines as recommended, leaving many at risk for serious flu illness.
“The most serious complication is respiratory failure, but there are other complications, such as inflammation of the heart,” del Rio said.
He is most concerned about respiratory failure, which may require intubation in the intensive care unit.
More news about the tripledemic
And there is a possibility that a hard flu infection could lead to “long flu.” As with Covid, there is concern that those infected with the flu could also have lingering long-term effects. Akiko Iwasaki, a professor of immunobiology at Yale University, told NBC News in November that it’s not unheard of to experience symptoms after the flu, especially lingering fatigue and brain fog.
However, more research is needed to understand the magnitude of the problem.
Is it worth getting a flu shot?
While the flu shot isn’t perfect, vaccination is the best way to help prevent these complications, experts agree. Full protection lasts about two weeks, and while it’s still possible to catch the flu after getting the shot, you’re less likely to get seriously ill because of that extra protection.
While there’s no data yet on how effective this year’s flu vaccine is, it appears to be a “very good match” with circulating strains, said Dr. Rochelle Walensky, director of the CDC, in a briefing last week.
Even after a case of the flu has been diagnosed, getting the vaccine is still important, as it provides broader protection against different strains of the flu virus. It’s possible to get the flu more than once in a season, experts say.
The current vaccine protects against four strains: two influenza A strains and two influenza B strains.
“It’s not too late to get the flu shot,” Chin-Hong said. “We don’t know when the flu season will end, and last year we saw a very long tail into the spring.”