The RNA vaccine against COVID-19 has many qualities, but it has a flaw that has not escaped anyone: the protection it confers is short-lived, hence the need for frequent booster shots. A study recently published in the Journal of Allergy and Clinical Immunology by a research team from France and Laval University suggests that this weak point in the vaccine could be due to a cascade of reactions that affect cells of the immune system, T lymphocytes.
“We believe that by blocking this cascade of reactions, we could improve immune memory and significantly extend the duration of protection conferred by this vaccine,” says the head of the study, Jérôme Estaquier, professor at the Faculty of Medicine of the Université Laval and researcher at the Research Center of the CHU de Québec – Université Laval.
Remember that the COVID-19 vaccine contains RNA which controls the production of a virus protein, the spike (S) protein, by human cells. “The body then mounts an immune response which will serve to prevent the development of the disease when it is confronted with the virus,” explains Professor Estaquier.
In a previous study, his team demonstrated that, in people suffering from severe COVID-19, a cascade of reactions triggered by the S protein led to a weakening of the immune response linked to the death of T lymphocytes. “Like the vaccine induces the production of protein S by the body, we wanted to know if the same cascade of reactions was present, at least temporarily, in people who are vaccinated,” specifies the researcher.
The Franco-Quebec team followed, for 28 days, 30 people who had just received a COVID-19 vaccine in order to measure different parameters of their immune response. The data shows that, as expected, protein S production increases in the days following vaccination. It reaches a maximum at 14e day and it disappears almost completely after 28 days.
-“The increase in protein S triggers the same cascade of reactions as that observed in people with COVID-19,” summarizes Professor Estaquier. One of the steps in this cascade is the production of reactive oxygen species which damages the DNA of T cells. We believe that this damage could explain why the body fails to mount a lasting immune memory and why it boosters are necessary to maintain protection against the virus.”
— Jérôme Estaquier
Professor Estaquier’s team now intends to test this hypothesis by using an inhibitor of reactive oxygen species, N-acetylcysteine, as a complement to vaccination. “It is an amino acid already used for different purposes in humans. We will administer it orally to people who have just received the vaccine. This will allow us to evaluate its effectiveness in protecting T lymphocytes and thus improve the duration of protection conferred by vaccination.
The COVID-19 vaccine is a good vaccine, insists Professor Estaquier, but the short duration of protection it confers is a significant drawback. “A large part of the population does not want to be vaccinated every six months against COVID-19. If we want to maintain high vaccination rates, we must listen to the needs of the population and find ways to correct this problem.
