COVID-19

Covid-19: five preconceived notions about vaccines we hear everywhere

The Covid-19 vaccination campaign continues to develop in France. An important milestone was reached this week: According to Public Health France, more than 30 million people – 31.9 million as of June 18 – received at least one dose of the vaccine, or nearly half of the population. Prime Minister Jean Castex said he was targeting 35 million French people fully vaccinated at the end of August – up from 18.2 million on Saturday.

After a hard start, the French vaccination campaign is going well: it was opened even to adolescents on June 15, the date originally planned for all adults has also been pushed back. But France is still far from reaching “77-80%” of the population, the threshold required for known herd immunity, according to Samuel Alison, director of research at CNRS and infectious disease specialist cited by France Info. …

However, many French women and men, not totally opposed to vaccination, remain reluctant or hesitant. Their concerns are easily fueled by the ideas they receive, which are circulated on social media, in the media, or among others. Reviews of ideas received are often shared.

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  • Covid vaccines were developed too quickly, we don’t have enough data

In February 2020, four months after the onset of the disease caused by SARS-CoV-2, the World Health Organization (WHO) estimated that there would be no vaccine against the disease until the fall of 2021. Six months later, WHO identified 168 vaccines in development worldwide, including 28 in the clinical impact phase; six of them were in phase III, the most advanced. There is no doubt that the development of these vaccines has gone much faster than we are used to.

However, “they weren’t developed too quickly,” insists L’Express Morgane Bomsel, CNRS research director and immunologist at the Cochin Institute. This is the result of decades of research on Covid-19. coincidence: we were able to apply the work on which people have been working for a long time. ”

Virologist Milen Ogliastro explains, for example, on the website of the National Research Institute for Agriculture, Food and the Environment (INRAE): “Understanding the virus, its mechanism of infection, its interaction with the host and the immune response is the longest phase of research (5-10 years). It determines which viral protein (s) will be the best candidate for a vaccine. In the case of Covid 19, previous research on coronaviruses and in particular the SARS-CoV epidemics in 2001-2002 and MERS-CoV in 2012 provided this knowledge. ” Thus, it has “won years of research” in vaccine development.

The speed of development of vaccines against Covid-19 is also due to the scale of international mobilization, fueled by the fact that the disease has affected everyone. “A lot of money has been invested in the development of vaccines in the private sector, focusing on work that is already well ahead,” says Morgan Bomsel. The first states to be vaccinated began in December 2020. Some, like Israel, are fast approaching herd immunity. “Looking back, and what we can observe in these countries [où la vaccination est avancée]we have data on the effects and efficacy of vaccines, ”recalls a CNRS researcher.

  • “I’m young, I don’t risk anything, so I don’t need to get vaccinated.”

“Whatever vaccination is, we vaccinate for two reasons: for ourselves and for others,” says Morgan Bomsel. We are part of society, and this is done in order to limit the spread of the virus. If we can walk without a mask, that’s good. because the circulation of the virus has decreased; and it has decreased in part because a large part of the population has been vaccinated. ”

Although young people without comorbidities are less likely to develop severe forms of the disease, getting vaccinated can help protect those around them who are at increased risk. And this, even if vaccines against Covid-19 do not prevent the transmission of the virus: “However, we are less infected than when we are not vaccinated,” the immunologist says.

In addition, there is no zero risk for young people, who can also develop severe forms of the disease. “The question that needs to be asked about young people is different,” says Morgan Bomsel. In the current situation, when most of the world does not yet have vaccines, wouldn’t it be wiser to give sera to countries that need them? instead of vaccinating adolescents? ”

  • “RNA messenger is a new method, I’m not sure”

Vaccines from Pfizer / BioNTech and Moderna, in particular, rely on messenger RNA. Classically, vaccination is based on the administration of a weakened or inactivated infectious agent or on the basis of some of its proteins. The idea behind messenger RNA vaccines is to allow our cells to produce a component from which our body can learn to defend itself. ” , explains the National Institute for Health and Medical Research on its website.

This is the first time that vaccines based on this concept have been licensed and used on such a large scale. But the technique is not new. According to the Pasteur Institute, it was opened in the 1960s. The technology behind messenger RNA vaccines was pioneered and developed in the 1990s, recalls INRAE’s Milen Ogliastro. The first vaccines were tested against Ebola and Zika viruses or against seasonal flu.

“It’s true that we don’t have as many prospects as with other types of vaccines,” admits Morgan Bomsel of CNRS. But RNA has the advantage of not being a replicative vaccine that remains in the body. After it has been used, it breaks down and is quickly eliminated from the body. Within a few days he disappears. ”

  • “Mass vaccination drives new options”

According to Daniel Flore, a vaccinologist and vice president of the Technical Committee for Vaccinations, interviewed by France Info, “It’s not vaccination that causes options. The reason for the appearance of variants is the intense circulation of the virus. ” Variants appear, in particular, with a mutation in the genome of a virus, when the latter infects the cells of an organism and “makes a mistake” by copying its genetic code. However, the mutations are facilitated by the strong circulation of the virus. The main known variants, such as the so-called “British”, “Brazilian” or “Indian”, appeared in countries where the spread of SARS-CoV-2 was very dense. “Anything that can reduce the intense circulation of the virus is likely to reduce the appearance of varieties,” recalls France Info Daniel Flore. Hence, vaccination will limit it.

However, “the idea is not absurd in itself,” says immunologist Morgan Bomsel. You might say, “Because you are limiting the spread of a virus that is sensitive to your vaccine, you are encouraging viruses that could not have appeared without it.” time to spread. But the reality for six months shows that this is not so. “According to the immunologist,” the problem with options is not that vaccines exist, but that they are not used everywhere, especially where Covid is spread. ” Covid-19 really remains very unequal in the world: “More than 75% of all vaccines have been introduced in only 10 countries,” said WHO head Tedros Adhanom Ghebreyesus at the end of May.

  • “RNA vaccines change our DNA”

“It’s impossible,” says immunologist Morgan Bomsel. “RNA doesn’t interact with DNA. But there is no possibility of integration. ” Messenger RNA cannot penetrate the cell nucleus, which contains the chromosomes that contain our DNA.

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“To integrate into our DNA, this RNA must be reverse transcribed in the form of DNA. [la transcription se fait normalement depuis l’ADN vers l’ARN, NDLR]… It will have to enter the nucleus and integrate into the genome, this is a very, very unlikely scenario of a catastrophe, ”explained last December Peace Celine Lacroix, Researcher, Laboratory of Tissue Biology and Therapeutic Engineering.


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