'Flurona' Is Not New: COVID and Flu Coinfection, Explained

Pedestrians in flu masks walking in city - stock illustration.

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Key Takeaways

  • The informal term “flurona” has been used to describe a rare coinfection of COVID-19 and influenza.
  • The U.S. is recording high case rates for both respiratory illnesses, increasing the likelihood of coinfections.
  • Lab studies indicate coinfections can cause more severe disease, though each person’s outcomes will depend on their individual health profile.

The term “flurona” is circulating the internet after doctors in Israel diagnosed a patient with both influenza and COVID-19 last week.

Flurona is neither a medical term nor a description of a new coronavirus variant. While the term is new, cases of simultaneous COVID-19 and flu infections are not. One of the first instances of COVID-19 in the United States, reported in early 2020, was a double infection case, according to The Atlantic.

As the U.S. battles a historic surge of COVID-19 cases, cases of influenza have been on the rise as the flu season progresses. Though there are few documented cases of flurona, experts say it’s possible that as the risk of viral transmission increases, so do the odds of getting both infections at the same time.

“Although it’s rare, it can happen since they’re two completely different viruses and both are rampant right now,” Purvi S. Parikh, MD, an allergist and immunologist at NYU Langone and national spokesperson for the the Allergy and Asthma Network, told Verywell in an email.

How Common Is Flurona?

Early last year, experts had warned of a possible “twindemic” with the possibility of overwhelming health systems. In the end, there was “essentially no flu,” thanks in part to COVID-19 mitigation strategies like masking and social distancing, Timothy Brewer, MD, MPH, a professor of epidemiology at the UCLA School of Public Health and at the School of Medicine, told Verywell in an email.

In the current flu season, the U.S. is seeing a substantial uptick in influenza cases. So far, the Centers for Disease Control and Prevention has reported 18,479 flu cases compared to 877 at the same time last year.

“If influenza cases are up, then the likelihood for coinfection will be higher too, particularly because these viruses are circulating at the same time,” Brewer said.

In a 2019 study, researchers estimated that 43% of surveyed patients hospitalized with a flu-like illness were infected with more than one virus.

Is Flurona More Dangerous?

Scientists still aren’t sure exactly how an influenza infection changes the severity of COVID-19 illness, and vice versa, though lab studies provide some clues.

In one study, researchers found that infection with influenza A may increase a person’s susceptibility to COVID-19 by increasing the amount of ACE2—the receptor that allows the virus to infect our cells—in the lungs. This may increase the odds of getting COVID-19 as well as the severity of that illness, the authors wrote.

An animal study published in October 2021 found that coinfection with influenza and COVID-19 led to more severe and prolonged pneumonia in hamsters.

In a meta-analysis published in PLoS One, researchers reviewed more than 6,000 studies of hospitalized and non-hospitalized patients and reported that 19% of COVID-19 patients experienced coinfection with another virus at the time of their COVID-19 diagnosis, and 24% had superinfections (another virus detected sometime after their COVID-19 diagnosis). For both groups, researchers found that the likelihood of death increased by more than three times.

While animal studies and retrospective reviews can be helpful in understanding how these viruses interact with the body, Brewer recommends caution when drawing conclusions in individual cases.

“Just reading about one case where somebody either did very well or did not do well isn’t necessarily going to tell you how most people are going to do,” Brewer said.

The severity of the disease likely depends on individual health profiles. For instance, people who have underlying heart and lung disease, who are older than 65 years, or have immunosuppression may be more at risk of COVID-19 and influenza. If coinfected, these individuals may be at higher risk of serious illness as well, Brewer added.

Preventing and Treating Coinfections

Brewer said hospitalized patients are tested for both COVID-19 and influenza during the flu season. Getting a precise diagnosis can be important, as each disease has different treatment options.

If you’re experiencing flu-like symptoms, get tested for COVID-19 as soon as possible. If you have a reason to believe you may be sick with the flu, experts recommend reaching out to your healthcare provider. They may diagnose you through a description of symptoms or by taking a nasal or throat swab test.

Taking an antiviral for flu, such as Tamiflu or Relenza, can shorten the course of illness and prevent complications like pneumonia. Antiviral medications may reduce the likelihood of hospitalization for people at high risk of severe disease.

Several antiviral treatments for COVID-19 have been made available, including remdesivir and the newly authorized oral drugs from Pfizer and Merck.

Being treated for both infections at the same time should be safe, Brewer said. These drugs target either influenza or COVID-19, and they don’t seem to induce adverse side effects if both taken at once.

Behaviors that can curb the spread of COVID-19 can also minimize flu infections, since both viruses are transmitted through respiratory droplets. Measures like wearing a mask, washing your hands, and maintaining physical distance from others can help protect you from both viruses.

Ultimately, the best way to prevent infection and serious illness is to be vaccinated for the flu and for COVID-19. It’s safe and effective to get both shots at the same time.

“Get vaccinated if you haven’t already,” Parikh said. “Flu season will last for many months to come, as will COVID.”

What This Means For You

Public health experts continue to emphasize that vaccination is the best way to protect oneself against both flu and COVID-19. Wearing a mask, social distancing, and hand washing minimize the spread of both viruses. If you are experiencing flu-like symptoms, get tested for COVID-19 as soon as possible and talk with your doctor about getting tested for the flu.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Weekly U.S. influenza surveillance report.

  2. Pinky L, González-Parra G, Dobrovolny HM. Superinfection and cell regeneration can lead to chronic viral coinfectionsJ Theor Biol. 2019;466:24-38. doi:10.1016/j.jtbi.2019.01.011

  3. Schweitzer KS, Crue T, Nall JM, et al. Influenza virus infection increases ACE2 expression and shedding in human small airway epithelial cellsEur Respir J. 2021;58(1):2003988. doi:10.1183/13993003.03988-2020.

  4. Kinoshita T, Watanabe K, Sakurai Y, et al. Co-infection of SARS-CoV-2 and influenza virus causes more severe and prolonged pneumonia in hamsters. Sci Rep. 2021;11(1):21259. doi:10.1038/s41598-021-00809-2

  5. Musuuza JS, Watson L, Parmasad V, Putman-Buehler N, Christensen L, Safdar N.. Prevalence and outcomes of co-infection and superinfection with SARS-CoV-2 and other pathogens: a systematic review and meta-analysis. PLoS One. 2021;16(5):e0251170. doi:10.1371/journal.pone.0251170

By Claire Bugos
Claire Bugos is a health and science reporter and writer and a 2020 National Association of Science Writers travel fellow.