25 Oct

I am sure you have already heard about these Influenza episods. Every year, the same story is repeated, we can see on TV or hear on the radio these advertisements for the vaccine of the year. Do you know the reason why every year, scientists have to produce a new vaccine? Let’s have a closer look to the disease.¬†¬†

What is Influenza ?

¬†This disease is caused by a virus called myxovirus influenza. These viruses are RNA (ribonucleic acid) viruses. This means that influenza’s genes are encoded into RNA. This virus will enter its host’s cells to infect it. Once it is done, the virus will then put its RNA into the cell. Infectious RNA will be recognized by the host cell and translated into proteins. This way, the virus uses its host to produce its own proteins and create other viruses to infect other cells. This is allowed¬†by assembling the viruses proteins all together. Influenza uses this method a many times in a row to produce a lot of viruses in order to¬†infect a lot of cells.

Now that you know this story, the question that remains is : why do we have to produce a new vaccine every year? In the rest of the article, we are going to focus on how is this vaccine produced and how it works.

The vaccine targeting influenza 

The first  step consists in identifying the virus. All the year long, virus samples are taken in different laboratories in the world and all these samples are sent to the OMS laboratories (Organisation Mondiale de la Santé). These laboratories are responsible for the vaccine development. As soon as these laboratories detect a virus strand that differs from the previously known strands, there is a risk of pandemic.

A pandemic is a transmission of the virus at an enormous scale. It is the kind of scenario that everybody wants to avoid, no matter what. Thus, scientists have to produce the virus in huge quantities to perform vaccinations.  However, a vaccine protecting against the new virus but not the previous one would not be very useful. Therefor we have to create a hybrid virus so that the vaccine can target both of them. The new virus and the previous one are then inoculated into chicken eggs to let them multiply. After a while, as the virus has a strong tendency to mutate (this is  the reason why the vaccine has to be changed every year), a hybrid virus will be naturally created. Thus, vaccination will be able to protect us against the new and the previous virus at the same time. Researchers have then to verify that the hybrid is able to produce the proteins that take place into the external layer of the virus. This is to make sure that the hybrid will be recognized and targeted by the antibodies when they will induce their production.

Unfortunately, these viruses are too dangerous to be used directly for vaccination. They first have to be inactivated. OMS laboratories kill viruses with chemical compounds such as formaldehyde, this way, there will be no more infection risks when the vaccine will be given to the patient.

Currently this vaccine is developped and produce to a large scale by the company Sanofi-Pasteur¬ģ which offers us a video to summarize this fabrication process.

Now you know more about this famous vaccine against influenza. I hope you will be convinced of its necessity mainly if you are a fragile person (old people, week immune system…).

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PhD Student in Biophysics

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