How could the flu kill a healthy 20-year-old in just two days?

If you’ve had the flu in recent years, you probably remember just how dreadful the respiratory illness can be: the muscle aches, the fever, the overall feeling of awfulness.

It’s well-known that people who fall into certain high-risk categories, such as young kids and seniors, can develop serious complications or even die as a result of influenza.

But people tend to overlook the fact that the virus can even take the lives of otherwise healthy individuals—as in the recent case of a 20-year-old woman from Phoenix, Ariz.

A mother of two infant boys, Alani “Joie” Murrieta died on Nov. 28, just two days after falling ill, according to a GoFundMe page set up by her aunt, Stephanie Gonzales.

Gonzalez told BuzzFeed News that her niece had gone home from work on Nov. 26 because she wasn’t feeling well. The next day, a relative took her to urgent care, where she was given an anti-viral medication to treat flu symptoms. By the following morning, she was feeling worse and began coughing up blood. She died that afternoon. Her infection had reportedly developed into pneumonia.

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“I still don’t understand how this happened to her so fast—she went from feeling a little sick on Sunday to going to urgent care on Monday and then being gone by Tuesday afternoon,” Gonzales said.

Flu-related deaths in otherwise apparently healthy people are rare. However, there are a few ways the virus can be fatal in such individuals.

The body’s immune system attacks the virus in the lungs by sending out cells and chemicals called cytokines, which cause severe inflammation, according to National Geographic. That swelling can cause blood and other fluids to build up in the lungs, causing the person to drown.

In other cases, with the immune system is using all of its energy and reserves to fight the virus, people end up susceptible to bacterial infections, the National Academies reports. Bacteria can multiply rapidly and can kill cells and tissues or cause a toxic immune reaction.

The flu can also lead to multiple organ failure.

“It’s not common to have fatal outcomes but certainly people can experience sever influenza,” says Dr. Michelle Murti, a public health physician at Public Health Ontario. “With the influenza outbreak of 1918, the people most likely to die were otherwise healthy young adults in their 20s and 30s.

“It’s an illness that basically shuts down your lungs,” she says, “and some people need serious intervention—ventilation and life support—to help pull through.”

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Besides kids under five and seniors over 65, other groups at high risk of severe complications or even death related to the flu include those with compromised immune systems or underlying health conditions such as asthma, diabetes, chronic obstructive pulmonary disorder and obesity.

Pregnant women are also vulnerable: Murti had a case where a woman who was 22 weeks pregnant and who had contracted the flu ended up losing her baby and was on life support herself for almost two months.

Influenza causes about 12,200 hospitalizations and 3,500 deaths in Canada each year, according to the federal government.

Most people, however, recover in about seven to 10 days.

“Some people have mild cases, but for most people it’s a fairly unpleasant experience,” Murti says. “You feel like you’re just wiped out, you feel like you’ve been hit by a truck. There’s fatigue, muscle aches, and that heavy feeling.”

Symptoms typically include the sudden onset of high fever, cough, and muscle aches, along with headache, chills, lost of appetite, and sore throat.

Murti emphasizes the importance of annual vaccination, which helps protect individuals from the illness and also contributes to reducing rates within communities, a phenomenon known as herd immunity.

There are other things people can do to help prevent the flu.

“Make sure you’re washing hands frequently throughout the day and that you’re eating well, exercising, and resting well to keep up your immunity,” Murti says. “Those are all important pieces of staying healthy in the winter.”

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