Question asked by Sandrine on January 2, 2022.
Hello,
You ask us about the multiple publications which assure, on social networks, that the “Flurona” is emerging, “Mix of influenza and Covid detected in Israel”. Originally, the information came from the Israeli media, and in particular from the online magazine The Times of Israel. In an article published on Sunday, he reported that the first Israeli case “Of a person infected with seasonal flu and Covid-19 at the same time” was confirmed Thursday by the country’s health authorities. And the article adds that “The two infections were discovered in an unvaccinated pregnant woman who had mild symptoms”, according to the details given by the hospital where she was cared for.
Contrary to what some viral publications advance, this combination between seasonal influenza and Covid-19 does not result from a new virus, or from a “fusion”, but simply from what is called a “co-infection “. In other words, two viruses responsible for different diseases affect the same individual at the same time, and are both sources of pathologies.
The word “Flurona” – which is not official since it is a nickname imagined by Israeli Internet users from the contraction between “flu”, diminutive of “influenza” (flu in English) , and “coronavirus” – could however suggest that a virus has been discovered. “This term is misleading”, considers Etienne Decroly, research director for the CNRS in Marseille and member of the French Society of Virology. Seasonal flu and Covid-19 being caused by “Two very distinct families of viruses”, “No proven risk of the emergence of a chimeric virus, or of recombination between these viruses, has been demonstrated to date”, wants to reassure the virologist.
Some French cases
The information was widely covered in media around the world – in France, by the local press in particular – with headlines having misled readers. Sometimes used in isolation, the expressions “first case” or “for the first time” helped to pass off, wrongly, this first Israeli case of co-infection as the first worldwide. However, the article in Times of Israel himself invited not to fall into this extrapolation, specifying that “Cases of patients with both influenza and Covid-19 appeared in the United States in the spring of 2020”.
Moreover, the “Flurona” is only the translation of a “A fact known for decades”, insists Alexandre Bleibtreu, infectious disease specialist in the infectious and tropical diseases department at the Pitié Salpêtrière hospital (in Paris): “It is possible to be infected with two pathogens at the same time, whether they are two viruses or one virus and one bacterium.” Thus, infections of both Covid-19 and influenza are nothing new, according to the doctor, since cases had been detected “From the first wave”, And this “Including in France, including at the Pitié Salpêtrière”. These co-infections are “Rare but not exceptional”, summarizes Bruno Lina, professor of virology at the CHU de Lyon, who for his part identified “One or two cases” in his institute.
Omicron would block viral interference
The emergence of double infections is made possible by “The co-circulation of viruses with a respiratory tropism associated with a reduction in barrier measures”, explains Alexandre Bleibtreu. In fact, on the one hand, the coronavirus responsible for Covid-19 and the classic respiratory viruses (those that cause influenza, bronchiolitis, or the respiratory syncytial virus) now circulate concomitantly – whereas immediately after the emergence of Sars -Cov-2, notes Bruno Lina, “The trend was towards the complete disappearance of other viruses.” And, on the other hand, while at the start of the crisis, all the barrier measures were generally well applied and containments had been put in place, preventing other respiratory viruses from circulating since they are also transmitted by by air, this is no longer the case today. “Lassitude, slackening in barrier measures reduces protection against all these respiratory viruses”, analyzes the Lyon virologist, who is also a member of the Scientific Council.
What is more, co-infections would be favored by the explosion of contaminations with omicron. This variant of the coronavirus would in fact be capable of blocking an immune response which normally occurs after infection with a virus: “viral interference”. That Bruno Lina details as follows: “When a cell is infected, it sends signals to other cells around it, telling them to defend themselves by producing interferon – a substance we all make and which naturally make cells resistant to infection. viral. ” On arrival, this phenomenon “Prevents viruses from accumulating one after the other in the same individual” (with, however, a lower level of protection in frail and elderly people). However, even if these are only hypotheses at this stage, “We have the impression that omicron is able to turn off this interfering function quite significantly”, Bruno Lina points out.
Cumulated, the co-circulation of respiratory viruses and the progression of the omicron variant, reinforced by a relaxation in the barrier gestures, make “likely” the appearance of new cases of co-infection, “Without them becoming extremely frequent”, estimates the professor of virology.
Increased mortality in the event of successive infections
Should we be worried? Currently, the available data do not allow us to measure the possible dangers of co-infections, and in particular to know whether they could promote the development of serious forms of Covid-19. In his article, the Times of Israel indicates that the Israeli Ministry of Health has launched a study to determine whether, in the case of this pregnant woman, “A combination of the two viruses may have made the disease worse.” However, as Bruno Lina reminds us, “These situations are so infrequent that we cannot establish a general law” on their consequences at this stage.
On the other hand, what we know from preliminary data from studies on successive infections is that contracting the viruses responsible for Covid-19 and influenza one after another increases the risks. “An increased mortality has been reported in people infected with the two viruses, compared to those who had only had Covid-19 or the flu”, explains Bruno Lina.