It's a COVID phenomenon that had, until now, gone relatively unnoticed: You can be infected with COVID-19 and the flu at the same time.
Thanks to the internet, it even has a name -- "flurona." And it will likely happen much more often this particular winter, as the flu season kicks into gear and the highly contagious Omicron variant continues to surge.
While the idea of battling both the flu and COVID-19 might sound terrifying, the same measures used to prevent the spread of COVID-19 also work against the flu, including masking and social distancing. And crucially, there are vaccines available for both viruses. The vaccines guard against severe infection, even if you are unlucky enough to catch flurona.
Flurona is not a distinct disease or a new variant, said Dr. Allison Messina, chief of pediatric infectious diseases at Johns Hopkins All Children's Hospital in St. Petersburg, Fla. The proper term is "co-infection," which describes when a patient is diagnosed with more than one pathogen simultaneously.
Co-infections are more common than you might think. You can catch two, three or more viruses simultaneously, including COVID-19. "Probably everyone has had a co-infection at some point," Messina said.
Long before the recent wave of flurona coverage, doctors were encountering all different types of COVID-19 co-infections. In a Journal of the American Medical Association study published in April 2020, researchers identified COVID-19 patients who were co-infected with viruses including rhinovirus and enterovirus (which are often the culprits behind the common cold), adenovirus (which can cause cold or flu-like symptoms), and respiratory syncytial virus (RSV), which can cause severe disease in young children and older adults.
Cases of flurona have also been reported throughout the pandemic, even as early as February 2020, when a man in Queens, N.Y. tested positive for the flu and COVID-19. Widespread awareness of the phenomenon started to pick up last week, after the Times of Israel announced that a pregnant woman came down with a co-infection that the publication dubbed flurona. Other cases have been reported in various parts of the United States, including Houston, Florida and Los Angeles.
For the time being, co-infection with COVID-19 and influenza is rare, and it will likely remain that way if flu activity continues to be suppressed.
During the past two years, the United States and much of the rest of the world have experienced historically low influenza levels. The flu seemed to be kept at bay by all the COVID precautions used during the pandemic, such as lockdowns, masking and social distancing.
"All of those things that you're doing to prevent yourself from getting COVID are probably the same things you can do to prevent flu as well," Messina said.
As social distancing measures relaxed in the fall of 2021, many experts feared the flu season would return with a vengeance, considering that flu vaccinations were down and the general population had reduced immunity to the virus.
While the flu season has so far been less severe than many feared, that could quickly and easily change.
"In most years, we typically see flu peak kind of anywhere between November, December, and into January and February, so I don't think that we can say yet how bad the flu season is going to be," Messina said. "It still could get worse."
Flurona will likely become a more common occurrence if it does, said Dr. Soniya Gandhi, infectious disease specialist and associate chief medical officer at Cedars-Sinai in Los Angeles.
"If we start to see a lot more flu in the community, it's possible that we could start to see co-infections if COVID is still very widespread," Gandhi said.
But some flurona cases may fly under the radar. As respiratory viruses, COVID-19 and influenza tend to cause similar symptoms. It would be challenging to know that you have a co-infection without being tested for both, and a health care provider typically conducts flu tests. Patients with a mild COVID-19 infection who aren't admitted to a hospital may never find out if they had a case of flurona.
Due to the low level of flu activity, too few cases of flurona have been studied to grasp its potential effects on patients. But experts seem to agree that having COVID-19 and influenza together is not ideal.
"Generally speaking, being co-infected with two potentially fatal respiratory pathogens is never a good thing," Gandhi said. "I think theoretically you can imagine if your immune system is trying to fight off two serious infections, that's going to be taxing."
Influenza and COVID-19 are respiratory viruses that attack the same region of the body: the nose, throat and lungs. Also, patients with compromised immune systems or underlying medical conditions are more susceptible to severe infections with both viruses.
"What we worry about with coronavirus and flu is that they both have the potential to be more serious viruses than some of the other viruses we see. Will that spur more severe disease? I think the jury is still out on that, but that's the fear," Messina said.
Fortunately, there are treatments available for both viruses. To avoid the possibility of flurona altogether, or to blunt its potential harms, vaccines make all the difference, according to Messina.
"Everybody over the age of 6 months is eligible to get their flu vaccine. And, of course, kids over the age of 5 can be vaccinated for coronavirus as well," Messina said. "So, I think the best thing you can do to try to avoid that from happening is to be up to date on both of those vaccines."
The U.S. Centers for Disease Control and Prevention has more on influenza and COVID-19.
SOURCES: Soniya Gandhi, MD, vice president, medical affairs, and associate chief medical officer, Cedars-Sinai, Los Angeles; Allison Messina, MD, chief, pediatric infectious diseases, Johns Hopkins All Children's Hospital, St. Petersburg, Fla.