What Happens If You Get the Flu and COVID at the Same Time?

Last year, the “twindemic” never happened. This year, experts are worried.

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a person checks a thermometer to see if they have a fever

Last year, experts feared a “twindemic” of COVID and the flu would overtake hospitals with people severely ill from either influenza or the coronavirus. Both respiratory diseases tend to ramp up in the colder months, but the 2020-2021 flu season was mild, partially because of masks and social distancing. Experts now suspect a rise in colds and flus this winter since people are burnt out and taking less precautions. They’re also more vulnerable to these viruses because precautions stopped them from circulating last cold and flu season, preventing people from building immunity.

As we can expect many people to get COVID or the flu this winter, it raises the question: Is it possible to have both diseases at the same time? More importantly, what will happen to your body if you do?

Flu and COVID Co-Infection

Though being infected by both viruses at once is possible, it’s probably rare, says Sunjay Mannan, a physician with the Allegheny Health Network in Pennsylvania. A study of 116 COVID-19 patients from last year found that about 21 percent were co-infected with some other pathogen. Only one of those pathogens was influenza.

Though there are few known cases of flu and COVID-19 co-infection, experts are probably missing some. “There are people who simply don’t go to the doctor when they have these symptoms,” Mannan says. “Those positives, we would be missing in the data.” It doesn’t help that symptoms are similar for both illnesses, so it’s nearly impossible to tell if a person has both without testing.

There are three main ways that viral co-infection can play out inside the body, Sarah Meskill, a professor of pediatric emergency medicine at Baylor College of Medicine in Texas, told Fatherly in an email. First, one virus may dominate over the other, so there is only one main infection. Second, the viruses may help each other replicate inside the body, which can make both infections worse. The third possibility is the most common: The viruses co-exist without affecting each other much.

Some experts think that when you get infected by either influenza or the coronavirus, your body ramps up your innate immune system, which can attack any virus. When the second virus infects you, you’re then better able to fight it off. Other experts think that co-infection of these two could worsen symptoms, especially because both viruses attack the lungs.

2021-2022 Flu Season

But co-infection isn’t the main concern for the upcoming flu season. Experts are worried that hospitals will be overloaded with sick patients. “Inner-city hospitals struggle every year taking care of the flu,” Mannan says. The mortality rate in nursing homes is high, and medical experts fear that the “twindemic” may take an especially nasty toll on the elderly. RSV is on the rise in kids too, much earlier than usual, creating concerns for the winter.

The best thing you can do to protect yourself from co-infection is to get both the COVID vaccine and the flu shot, the latter of which the Centers for Disease Control and Prevention is pushing for nearly everyone older than 6 months of age. Even if you expect you could walk off the flu, get the shot, because it’s not just about you. “With any vaccine, the key thing is herd immunity,” Mannan says. “We’re trying to protect those in the community who are truly at risk.”

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