Co-infections of the flu and COVID-19 (colloquially dubbed "flurona") are unusual, but they will likely become more common this flu season.
One man who had flu and COVID-19 at the same time in December said the worst of it lasted about 48 hours, and included terrible night sweats.
Experts stress getting vaccinated for both the flu and COVID-19 will reduce your odds of getting co-infected.
When Jamie Grayson first started to feel sick in mid-December, he didn't think much of it.
"It felt like I had like a sore throat," the baby gear expert told Insider. "Like I'd just been yelling at bars."
But as his symptoms progressed over the course of a few days, he started to wonder if this was more than just a case of laryngitis. He had just been visiting friends in New York City, "where it's like a hotbed of Omicron right now," he said.
"As I started to develop a cough, I was like, 'mmm, something's wrong.'"
Grayson started to wonder if he might've picked up COVID-19, and went to a clinic to get tested.
"I changed my flight back home, because I wanted to make sure I got a negative test before I got on the plane," Grayson, who lives in Denver, said. "It just felt responsible."
Though he is fully vaccinated against the coronavirus (with Johnson & Johnson's one-shot vaccine) Grayson hasn't had a booster shot yet, and he didn't get a flu shot this year, either. At the clinic, based on his symptoms and vaccination status, clinicians tested him for both the flu and the coronavirus. To his surprise, both tests turned up positive.
Disease experts call what Grayson had a "co-infection," but you may have heard of it recently as "flurona." Whatever you want to call it, a co-infection like Grayson's is nothing to panic about, but it is a reason to make sure you're up to date on both your flu and COVID-19 vaccinations this winter.
"I was luckily vaccinated, and it was fairly mild," he said. "I don't understand what the big deal is, to be honest."
"Flurona" is what scientists call a co-infection
"Flurona is not a term that we use at CDC," Alicia Budd, an epidemiologist at the Centers for Disease Control and Prevention's influenza division, told Insider.
The term popped up recently after a slew of coronavirus-influenza co-infections were diagnosed, first in Israel, and then in California, Texas, Kansas, Mississippi, and North Carolina. Infectious disease experts generally agree with Grayson that a co-infection is not a "big deal," at least for most people.
"It's the very unlucky individual who ends up with two respiratory virus infections at the same time," Budd said.
The reason that we haven't heard much about flu-COVID-19 co-infections before now is because the flu barely circulated at all last year, virtually disappearing (at least temporarily) as a result of COVID-19 lockdowns, as well as widespread masking and social distancing measures.
Budd says coinfections "could happen with any two viruses that are circulating at the same time." We've seen it play out before with RSV and flu, and different strains of flu. "This is not a situation where these two viruses are merging," Budd said. "This is a situation where one unlucky individual has gotten infected with two separate viruses."
The CDC has one hospital surveillance system called FluSurv-NET that may be able to provide some clues in the next few weeks as to how common flu-coronavirus coinfections really are, at least among hospitalized patients, Budd said.
"That looks to be very uncommon at this point, but it's certainly something that we're going to continue to monitor through that system," she added.
Flu and COVID symptoms are hard to disentangle
For Grayson, one of those "unlucky" early recipients of a dual coronavirus-flu infection during this pandemic, the worst symptoms lasted for about two to three days.
His sore throat at one point got so bad he said "it felt like razor blades were shoved down my throat because of the coughing situation," and he said he "had these wild body chills and sweats to the point where I would have to switch my bed, and rotate in the middle of the night, because my sheets were soaking wet."
After that "rough two to three day" patch, though, he started feeling better save for a "remnant cough."
He spent the next 10 days in isolation, to prevent spreading his illnesses. The clinic had advised him to keep close tabs on his respiratory symptoms, and seek ER care if he had any trouble breathing. Since he didn't, he simply rested, "hung out, watched a lot of Food Network, and hydrated."
He didn't lose his sense of taste, or smell, which used to be hallmark signs of contracting COVID, but are becoming less common now.
"It was fairly mild, aside from the sweats," he said, describing them as "full body drench, one leg under a blanket, the rest of my body sprawled out on the bed, fully uncomfortable, terrible."
How your body responds to having flu and COVID-19 at the same time
Getting sick with more than one virus at a time may increase - or even decrease - the severity of each illness. It depends on the person, and which viruses are involved.
For example, researchers in Norway did some research in the late 1970s and early 1980s that suggested seasonal flu infections may have prevented some RSV infections in children at certain times of the year. Similarly, in some instances, being infected with one strain of the flu might prevent a person from catching another one at the same time - in others it may not.
Dr. Carolyn Goldzweig, chief medical officer at Cedars-Sinai Medical Care Foundation, said the level of concern practitioners have for a coinfection "really depends on the frailty of the patient."
"A patient who has a normal immune capacity is probably going to mount an immune reaction, and they're gonna try and fight off both viruses," she said. In that case, "it's kind of just symptomatic treatment for both. Tylenol for fever and aches, and push the fluids, and rest, and that kind of thing."
Budd agreed that the concern is really: is this patient very vulnerable to COVID-19 or the flu in general? "People who are prone to a more severe infection with either of the viruses are probably going to have a more difficult time handling it if they're infected with both," Budd said.
For those high risk patients, doctors can prescribe antiviral drugs, such as Tamiflu for flu and PAXLOVID for COVID-19. Taken early, they can help prevent hospitalization and death in vulnerable patients.
How to prevent flurona
Both Budd and Goldzweig said the first prevention measure to emphasize is vaccination, for both COVID-19 and the flu. It's not too late to get your flu vaccine, if you haven't yet.
While it's true that the strains targeted by both the flu shot and the COVID-19 vaccines aren't perfect matches for what's circulating right now, the vaccines not only make it less likely you'll get a coinfection in the first place, they also make an infection milder, quicker, and easier, if you do get it.
"A lot of people don't get the flu vaccine," Goldzweig said. "In younger people, the flu can put you outta work for weeks, you know, it really can floor you."
Grayson says he's "very happy" that he was vaccinated against COVID-19 before he got his flu-coronavirus co-infection.
"I know people who are not vaccinated right now, and they have been sick for two weeks with this," he said, referring to unvaccinated friends who've caught COVID recently.
He said if he hadn't been vaccinated, "I don't know what flu and COVID would've done, to be honest."