Dr. Vivian Luchsinger: "Should get a flu shot, that is the principal called against influenza virus"

Dr. Vivian Luchsinger: "Should get a flu shot, that is the principal called against influenza virus"

Over the past few days, we have witnessed the media unusual preponderance of the need to be vaccinated against a future and possible flu outbreak. While campaigns are present year after year, there have been few occasions when the message has been given with this priority. This special motivation for citizens to be vaccinated relates to what happened on the north side of the map, where the rates of the sick and deceased from the influenza A H3N2 virus have been considerably higher during the season, compared to other years.

There are those who attribute this epidemic to factors such as cold and harsh weather conditions faced by Northern Hemisphere countries; however, the main factor in the magnitude of epidemics by this infectious agent is its known ease of change, so existing vaccines, even if they generate a response from antibodies that recognize the viruses contained theree, will not identify one that is different. That's the complexity.

Collecting this background, both the medical and scientific community, they have made a powerful call to the population, so that they are empt regardless of the age range, since this prevents the development of potential serious pictures, which in some cases could trigger pneumonia and even death.

To clarify certain aspects related to the influenza virus and the preventive measures to be taken before this infectious agent, the Society of Biology of Chile spoke with Dr. Vivian Luchsinger Farías who is a physician, doctor of science and researcher of the Virology Program of the Institute of Biomedical Sciences (ICBM), Faculty of Medicine of the University of Chile.

How does the flu virus work? And how complex is it?

First, it is important to clarify that there are three types of influenza viruses (A, B and C), and within them, there are also several subtypes, which are determined by the different proteins present on their surface, which vary most frequently in the case of the influenza type A virus. The implication of this is that if we have antibodies against subtype A H1N1 they will not recognize and therefore will not counteract the infection if we are in the presence of an H3N2 A virus. These differences are not alien to the influenza virus, since their variability is a natural property of them.

Why this variety?

It is mainly due to its biological structure, both the type of nucleic acid and the way it replicates.

In this sense, this type of virus is always varying, because the enzyme that replicates ribonucleic acid (the genome of this virus) does so in the wrong way, making mistakes in creating new copies to create "child viruses". This is how each descending virus can have differences with the "mother" virus. In addition, the changes are favored by the fragmentation of the genome of these viruses, in such a way that when an animal becomes infected with different strains of influenza at the same time, as can occur in the pig, during the replication of the viruses occurs what we call a reordering, generating new different viral particles because they have fragments of the viral genome of different origins. Both facts determine the natural ability to constantly change influenza viruses.

Is it always advisable to be alert to influenza?

There are always several subtypes of influenza virus circulating, so you have to be aware. It's not like one year I attack only one type of flu, there's a latent mix.

Under this scenario, when a large change occurs in one of the types of viruses we know, causing the appearance of a very different agent, we are at risk of a pandemic, since even if we have antibodies against those previous strains, they will not be effective against the new ones. This graphs what happened in 2009 with influenza A H1N1. In the latter case, the new virus was a triple reorderer, with fragments of the genome coming from three different origins (bird, pig and human), so it was a very different virus from the previous ones, and therefore people were not immunized, on the contrary, we were susceptible.

Global surveillance

There is global surveillance to know which viruses are circulating and based on it, it is defined each year which viral strains will be in the vaccine, so it is so necessary to be immunized annually, since the vaccine formula may be different each period. The government prioritizes the delivery of vaccines to those cohorts of the population most at risk, such as: pregnant women, older adults, infants or those with a basic disease, as they may develop pneumonia and require hospitalization. However, this does not exempt the recommendation to vaccinate all people, of all age ranks.

Why have the alarms about the importance of getting vaccinated sounded stronger this year?

This year the epidemic in the Northern Hemisphere was greater than in other periods, this as indicated by figures from the U.S. Center for Disease Control and Prevention (CDC), which showed a higher percentage of patients with flu complications, as well as an increase in the number of deaths from the virus.

With this background, the call is for society to get vaccinated, because it is expected that the same thing will happen in the Southern Hemisphere. Although it is not an established correlation, it is still advisable to get vaccinated year after year.

How is the flu vaccine made up?

The vaccine contains proteins from viruses, allowing us to develop antibodies to defend against infection. These, by definition, contain 3 or 4 viral strains (proteins of 3 or 4 viruses). On the other hand, and because the vaccine has no viruses capable of infecting, there is no chance that people will get sick from this source, as the viruses are not complete. What could happen is that the antigen, being a protein foreign to the body, causes fever and/or swelling at the injection site, but is mild and transient. Influenza vaccines do not cause this disease.

How are we currently positioned versus decades ago in aspects of health protocols and scientific research associated with influenza virus? Have we moved on?

Of course progress has been made. First of all, the vaccine is available. In addition, other vaccines have emerged that may be even safer than the current one, which is produced in egg, giving space for many times, even after the purification process, to remain some proteins of it that potentially generate some type of allergy. In this sense, new production processes are being tested, in different matrices, even safer than the egg. At the same time, we have antivirals against the influenza virus, and we didn't have that before.

This last point is key, and for antiviral to be effective, it has to be administered promptly, because the virus is able to replicate very quickly, and although the antiviral inhibits the process, if it is supplied when the cells are already replicating the virus, it is late to perform its work. That is why the indication is to supply the antiviral for the first two days after the onset of the disease.

What is your current research project? What line is it focused on and how does it come with the flu study?

In my current FONDECYT research project, we studied adults with community-acquired pneumonia (e.g. who became infected at home or at work), and one of the causes is the influenza virus. In this sense, and since in previous projects we observe that viruses are important, we are focused on analyzing the immune response of people, which could explain why there are those who do not develop a serious disease versus others who do, even if they do not have previous risk factors. In this project we try to find some marker, derived from some immune response parameter, that predicts how the picture will develop after infection with the virus to determine whether or not it will present a serious disease, in this way, and if we can find that marker, we could eventually analyze whether or not the patient should be hospitalized.

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Journalist:Patricio Grunert Alarcón. ®

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