An immune deficit which targets the way of type 1 interferons explains almost a quarter of these severe forms, despite two doses of vaccines.
Le Monde science and medicine
It was a scientific and medical enigma. Why do some people develop serious forms of COVID-19 despite two-doses vaccination? This, even though this vaccination induced, in their body, the production of antibodies capable of neutralizing the SARS-COV-2. For almost a quarter of them, an immunological deficit is involved, according to the results of International work published in June in the journal Science Immunology, and piloted by a French team .
The cases of these patients are however very rare. A total of 48 of them were recruited – in Greece, France, Turkey, Macedonia, Ukraine and the United States – in a study coordinated by Inserm teams, Paris Cité University and the Institut Imagine (Necker-Enfants Malades AP-HP and Rockefeller University in New York). Aged 20 to 86 years old (median age: 53 years; 34 men and 14 women), all had made a severe form to COVID-19 criticism which led them to resuscitation, following an infection by the Delta variant , despite two doses of RNA vaccine.
The authors first verified that, in these patients, the vaccine had been effective: the aim was to discover the origin of severe forms not linked to a failed vaccination. Six patients were dismissed from the study, because the vaccine did not induce neutralizing antibodies, either because they took immunosuppressive treatments, or because they were infected with HIV or that they were treated for lymphoma…
In the remaining 42 patients, the authors sought the presence of a completely different category of antibodies: antibodies which target certain molecules of our immune system, type 1 interferons (IFN-1). Faced with a viral infection, these IFN-1s constitute the very first line of defense of our body. In rapid response to the attack on a virus, they are produced by our cells and inhibit the replication of the virus in our infected cells.
Action of autoantibodies
Why look for these antibodies? A series of previous work had been carried out in non -vaccinated people. About 20 % of cases of serious pneumonia, resulting from an infection by the SARS-COV-2, were explained by anomalies (of genetic or immunological origin) weakening the immune response carried by type I interferons, had shown These same researchers.
But they were unvaccinated people. What happens to people who have received two doses of vaccine? The authors reveal that 24 % of them (10 out of 42) present “autoantibodies” neutralizing the action of type 1 interferons (autoantibodies are antibodies that attack the own constituents of an individual ). These autoantibodies were present before the SARS-COV-2 infection. Apart from this peculiarity, these patients did not have other immunological deficits and had no history of severe viral infection.
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