The news caused a stir: In Israel, a pregnant woman was infected with two viruses at once: the Covid-19 and the flu. According to the Israeli authorities, cited by The Times of Israel, this woman was hospitalized in Tel Aviv and not vaccinated once morest these diseases. She came out on Thursday in good health. Quickly, the idea of an alleged “fusion”, baptized “Flurona”, made the headlines.
In reality, it is rather a coexistence of two viruses. Cases of double infection of Covid-19 and influenza were identified as early as 2020, in several countries. A rare situation, say doctors, because viruses don’t like being together. This is also the reason why the arrival of a variant quickly supplants its predecessors.
Is co-infection dangerous?
“It’s so unusual that we lack reliable data, we have no answer to this question,” cautiously advances the infectious disease specialist Olivier Bouchaud, head of the infectious and tropical diseases department at the Avicenne hospital in Bobigny. But since the symptoms are mostly the same, a sick person can carry both viruses without realizing it.
“In times of flu, we systematically carry out PCR tests for Covid and influenza, which is how we accidentally discovered patients carrying both viruses,” explains Olivier Bouchaud. If the case of the pregnant Israeli woman has been particularly publicized, it is therefore nothing new or extraordinary: several people in France, and elsewhere in the world as well as in United States and in China, have experienced the same double infection. Sometimes developing classic mild symptoms.
A Bichat hospital study, carried out during the first wave of Covid-19, shows that 6% of patients hospitalized for Covid were carriers of another infection (rhinovirus, flu, etc.). “Co-infections can lead to viral interference, a virus limiting or suppressing the replication of the second virus, or to an increase in the severity of the disease compared to mono-infection”, conclude the authors. “These are two pathologies that will damage the lung tissue. And your immune system will be overwhelmed, ”also warns infectious disease specialist Benjamin Davido.
What does this say regarding our immune system?
Here once more, there are insufficient data on this subject to provide a formal answer. But co-infections may develop more in people who have weaker immune systems. “The case of the pregnant woman is not completely innocent, the immune system slows down to tolerate the fetus during pregnancy”, notes Olivier Bouchaud.
At the start of Covid-19, scientists used the profile of the H1N1 flu to determine the risk factors: obesity, diabetes, hypertension, pregnant women. “They turned out to be correct, the two viruses have the same preferential target,” recalls Benjamin Davido.
Does the Omicron variant promote double infection?
There is no reason to think so. Co-infections existed before its onset. The “downside” would be the haute propagation d’Omicron : “If it causes many more cases than the others, mechanically, the probability of co-infection is greater”, specifies Olivier Bouchaud.
Only barrier gestures and flu vaccination and the Covid-19 make it possible to effectively curb this risk, the infectious diseases specialists agree. “The lockdowns have collapsed all the viruses. And the barrier gestures gave having a hard time with the flu and bronchiolitis, especially in 2020 », Continues Benjamin Davido.
“Weariness, slackening in barrier measures reduces protection once morest all these respiratory viruses”, analyzes virologist Bruno Lina, member of the scientific council, in Release.
While France is currently suffering the full brunt of the double vague Omicron et Delta, the peak of the flu often appears in early February. Hence the importance of maintaining barrier gestures, even following this fifth peak in Covid cases. “The question is, how long will the Omicron wave last? asks Benjamin Davido. Because if the Covid curve goes down soon, the flu might take over. »