Being infected with the flu before contracting COVID-19 reduces the latter’s ability to replicate

There is no doubt that the arrival of the COVID-19 has conditioned much scientific research of the past two years. We know more and more about this virus and its effects on the human body. But there is still much to learn. Especially regarding its relationship to other viruses.

This is exactly what a of the latest studies published in the ‘Journal of Virology’. severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the flu virus A (IAV for its acronym in English and popularly known as influenza) are similar in many ways: Both are airborne pathogens, they are highly transmissible with pandemic capabilities.

They cause similar symptoms (fever, cough, fatigue, sore throat), but they affect some people differently and in fact, in general, COVID-19 seems to cause more serious illnesses in some people.

Also belong to distinct virus families (SARS-CoV-2 is a member of the Coronaviridae family, while IAV is a member of the Orthomyxoviridae family), but both have shown zoonotic potential, the ability to jump from animals to humans.

Double contagion: what can happen?

But, What happens when both infect a person? The study authors, led by Benjamin tenOever, analyzed the interaction between SARS-CoV-2 and the influenza virus during co-infection. The tenOever team performed both experiments on cells in culture as well as on an animal model (Syrian hamster, Mesocricetus auratus).

To animals the 2 viruses were administered simultaneously and examined on days 1, 3, 5, 7 and 14 post infection. Experiments were also performed in which they were first inoculated with one of the viruses, followed three days later by the other virus, and monitored 1, 3 and 5 days after the second infection.

What they discovered is that SARS-CoV-2 infection does not interfere with influenza virus biology, when subsequently applied. There was also no interaction when the two infections were simultaneous.

On the other hand, they observed a significant loss of replication capacity (viruses replicate, do not reproduce) of SARS-CoV-2 after an influenza infection. These data suggest that the co-circulation of SARS-CoV-2 and influenza is unlikely to result in an increase in disease severity. In fact, the host response to both viruses was comparable to that of SARS-CoV-2 infection alone.

“What we discovered – explains tenOever in a communicated – does the virus influenza interferes with SARS-CoV-2 replication in the lungs, even more than a week after IAV virus removal. In contrast, influenza showed robust replication in the airways of hamsters, independent of the presence of SARS-CoV-2. These data suggest the presence of intrinsic or induced factors by IAV that can limit the growth of SARS-CoV-2, but it is not yet clear whether this effect plays a role in disease severity. The research is important because the human population now has 2 circulating respiratory RNA viruses with high pandemic potential: SARS-CoV-2 and influenza A. Since both viruses infect the respiratory tract and can lead to significant morbidity and mortalityit is imperative that we also understand the consequences of co-infection.”

Despite the interest of these results, it must be taken into account that they were carried out in animal models. Exactly how it affects humans remains to be seen.. It is assumed that the general results may be similar, but it is still unclear whether it can have different effects depending on age, sex and whether diseases such as diabetes or lung and blood disorders can have a gravitational pull that tips the scales one way or the other. ‘other. In this sense, the The tenOever team notes that this is a first study and it will be necessary to deepen this knowledge.


Why can I be negative in an antigen test and positive with a PCR at the same time?

Leave a Comment