“The undeserved fame of flurone”: what is this double infection and why is it not rare

Before activating the alarms, we must ask ourselves if this fact is truly important or just one more phenomenon that occurs and occurred long before the pandemic with a greater frequency than we think.

We may once again have too much noise for so few nuts.

Of them, most produce very similar symptoms such as sinusitis, pharyngitis, laryngitis, tracheitis, bronchitis, etc, etc … That is, infections of the respiratory tract that cause inflammation.

Regarding local inflammation, it only represents the activation of the immune system against viral infection, regardless of the virus.

A few years ago a study was carried out on viruses that live with us and that are located in the lungs and they were found up to 19 different types.

These viruses are the roundvirus (You can imagine why they are called that) and they do not cause disease unless our immune system is somewhat damaged.

The relationship between virus and disease is relatively complex since everything depends on the severity of the symptoms they produce.

In many cases, the symptoms are so mild that we do not even appreciate them since the relationship between the virus and the immune system does not produce aggressive responses.

In other cases even viruses are useful for prevent other diseases as bacterial infections, since the cells they infect are not ours but bacteria and thus they control the population of bacteria that could cause us diseases.

You know, “the enemy of my enemy is my friend.”

The relationship between microorganisms and the immune system it is established since we are born.

We are subjected to invasion by multiple microscopic bacterial or viral organisms from birth and our survival is determined by our body’s ability to keep them at bay.

People suffering from immunodeficiency know very well that not having an efficient immune system turn them white even the most innocuous microorganism.

There we have the example of HIV patients and the recurrent and deadly diseases they suffered before the antivirals arrived.

Since the beginning of the pandemic, there has been some suspicion of the coexistence between the flu wave and the coronavirus wave.

It is not because they are two similar viruses, which they are not, but because both can cause saturation of the health system separately, as they have already shown.

Influenza viruses belong to the great family of the ortomixovirus. In this family we have influenza viruses A, B, C and D.

Of them, A and B cause the seasonal epidemic that visits us year after year (except last year thanks to social isolation measures).

Specifically, influenza A are those that cause pandemics while B have less travel, C create mild diseases and are not considered pandemic and D essentially affect livestock.

Flu viruses contain two proteína important in their membrane that characterizes them.

It’s about the hemagglutinin(H), which serves to infect cells by binding to a membrane sugar – sialic acid – and the neuraminidasa (N), which use the new virions to separate from sialic acid and infect a new cell.

In humans, 18 types of hemagglutinin and 11 types of neuraminidase have been characterized and their combination determines the type of virus that affects us year after year.

Some combinations have been shown to be very lethal, such as H5N1, but they have not presented the ability to disperse among humans with ease, for now.

Another big difference between flu viruses and coronaviruses is their genome.. While in influenza viruses the genome is made up of 8 pieces of negative RNA, that of coronaviruses is made up of a single strand of positive RNA.

This assumes that the respective genome replication mechanism is very different.

In addition, in the remote assumption that both viruses infect the same cell, it is impossible for combinations of their genomes to occur that can give rise to a viable virus with hybrid characteristics.

The possibility, if it existed, would be extremely remote and would be a true molecular surprise.

The danger of co-infection with two aggressive respiratory viruses such as SARS-CoV-2 and an influenza virus in unison would be found in the response to the infection, that is, in the symptoms.

Seasonal flu is capable of produce thousands of deaths annually by itself even in vaccinated people, as their immune systems cannot fight off the infection.

Therefore, if both viruses co-infect an immunologically depressed person, their combined action would generate known symptoms such as pneumonia, cytokine storm and multi-organ failure that also occur in cases of influenza, respiratory syncytial virus, pneumococci and others respiratory pathogens separately.

Apart from this problem, which is already worrying in itself, the other speculations about the recently christened disease with such an unattractive name should be considered nothing more than speculations lacking a solid scientific basis.

In any case, it should already be clear that to be prevented against influenza and SARS-CoV-2 infection the best strategy is boosting the immune system with vaccination.

* This article was originally published on The Conversation. You can read the original version here.

Guillermo López Lluch is cProfessor of the Cell Biology area, iAssociate researcher at the Andalusian Center for Developmental Biology e iInvestigator in metabolism, aging and immune systems and antioxidants on the Pablo de Olavide Universityin in Seville.

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