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Health A to Z  —  7 minutes

Flurona: Is it cause for concern? 

March 10th, 2022
Biron Team
Biron Team

At the beginning of the pandemic, clinicians were concerned about the effects of possible co-infection with SARS-CoV-2, responsible for COVID-19, and the flu virus, responsible for seasonal influenza.[1] However, it was not until January 2021 that the term “flurona,” a contraction of “flu” (for influenza) and “rona” (for coronavirus), appeared and ignited social media.[2] What are the dangers of this co-infection?

Influenza and COVID-19: A worrisome cocktail 

Beginning in early 2020, a number of concerns were raised about what impact the arrival of seasonal influenza would have later in the fall in the middle of a COVID-19 pandemic, since each of these two respiratory infections is potentially fatal in the elderly and those with weakened immune systems. Imagine a combination of the two! But since no knowledge of this possible co-infection existed, the only recommendation was vaccination against the seasonal flu, complemented by the COVID-19 vaccine once it became available. 

However, due to health measures such as mask wearing, physical distancing and hand washing, there was no significant flu activity in 2020-2021. Only four cases were confirmed in Quebec at the end of the flu vaccination period (32 in Canada), compared to several thousand cases in previous years.[3]   

An unlocalized threat 

Therefore, fears faded until January 2021, when Israel reported a first case of co-infection with SARS-CoV-2 and the flu virus in a pregnant woman.[4] This was when the term “flurona” first appeared. However, while the article was careful to mention that it was the first documented case in Israel, it was not the first co-infection in the world.  

As early as March 2020, a co-infection had been diagnosed in a New York family.[5] As well, in December 2021, a meta-analysis focused on more than 900 cases of co-infection reported in the scientific literature since the beginning of the pandemic.[6] 

The true extent of co-infection 

Although some cases have been identified, the precise number of co-infections is not known for three reasons:  

  1. The PCR tests that have been used to detect COVID-19 cases were not developed to simultaneously detect other micro-organisms (e.g., viruses, fungi or bacteria) responsible for respiratory illness.   
  2. Tests that can detect different respiratory infections, such as the respiratory multiplex PCR assays available at Biron, are not designed for the mass detection required by the COVID-19 pandemic.   
  3. Tests to detect influenza A and B antigens were rarely prescribed during the pandemic.   

However, the actual number of SARS-CoV-2 and influenza co-infections is thought to be quite high.  Viral co-infections are not new and are more common than previously believed. Different studies conducted prior to COVID-19 indicate that co-infections can affect anywhere from 14% to 70% of individuals hospitalized with respiratory illness.[7]  

Little-known dangers 

Because the number of confirmed cases is so small, it is difficult to know whether co-infection is more dangerous than single infection. The case reported in New York at the start of the pandemic was described as severe, while the case of the woman in Israel was rather mild.    

A meta-analysis of 12 studies involving 9,500 individuals with both COVID-19 and influenza appears to show that co-infection has no significant effect on disease severity and mortality. However, this conclusion should be interpreted with caution. Mortality was lower in Chinese studies, but higher in studies from other countries.[7] Therefore, further research is needed before a statement can be made about the dangers of co-infection. 

One thing is certain: It is not a new virus         

When the co-infection case was announced in Israel, many people, based on their knowledge of variants, mistakenly thought that flurona was a new super virus created from two viruses that had merged.   

This type of merger or recombination is possible when both viruses are from the same family. However, this is not the case with SARS-CoV-2, which belongs to the coronavirus family, and the influenza virus, which belongs to the orthomyxovirus family. Furthermore, their origins are different: the flu virus originated in birds, while SARS-CoV-2 very likely comes from a mammal (bat, pangolin). The structure of the two viruses is also very different, which does not favour the possibility of a merger.[8]  

Putting an end to infections 

During the pandemic, we learned that to stop the spread of SARS-CoV-2, we need to avoid close contact, practise good hygiene and get vaccinated. The same is true for the influenza virus: avoid contact with infected people, wash your hands and get vaccinated.   

These measures are especially important because the flu virus could return with a vengeance during flu season and further weaken our hospital capacity. After two years of low flu activity, far fewer people have natural immunity to influenza, which could increase the spread.   

To fight co-infections of COVID-19 and influenza, the solution is simple: encourage all at-risk individuals to get vaccinated against both types of infection. There is no need to invent a new word such as “flurona” and create confusion.  

For professional support, we’re here for you.

We provide services that can help your doctor diagnose COVID-19 and related respiratory problems.

  1. Marine Corniou (August 27, 2020). “Grippe et COVID-19: vers une épidémie double à l’automne?” Québec Science,
  2. Julie Charpentrat, AFP (January 4, 2022). “La double infection grippe et COVID surnommée "flurona" n’est ni inédite ni une ‘fusion’ de deux virus,” Imazpress,,145580.html
  3. Comité sur l’immunisation du Québec (December 11, 2020). “Fin de la campagne de vaccination contre l’influenza pour la saison 2020-2021,” INSPQ,
  4. Aryeh Stern (December 30, 2021). “Israel Reports First Case of 'Flurona',” Hamodia,
  5. Roxanne Khamsi (November 17, 2021). “The Double-Whammy COVID-Flu,” The Atlantic,
  6. Z. Guan, C. Chen, Y. Li et al.  (2021). “Impact of Coinfection With SARS-CoV-2 and Influenza on Disease Severity: A Systematic Review and Meta-Analysis,” Frontiers in Public Health,
  7. Lubna Pinky, Gilberto Gonzalez-Parra, Hana M. Dobrovolny (2019). “Superinfection and cell regeneration can lead to chronic viral coinfections,” Journal of Theoretical Biology, 466:24-38,
  8. Jean Ruelle. “Quelles sont les différences entre le coronavirus et la grippe saisonnière?” UCLouvain, [consulted on February 23, 2022]
Biron Team
Biron Team