This is a recommendation from the High Authority for Health, which is now confirmed by a study: the second dose of the Pfizzer or Moderna vaccines (the only ones that have been tested) is of no interest when it is injected into a person. cured of Covid-19.
On the contrary, even: it could cause more side effects.
Published in the "New England Journal of Medicine", this analysis, conducted by scientists at the Icahn School of Medicine at Mount Sinai, in New York, involves blood samples from 110 people, 67 of whom had not already been tested. infected with the virus and 43 were infected.
The results showed that after the first dose, participants who had already had Covid-19 "quickly developed titers (
Editor's note: medical term meaning concentration or level
) of antibodies that were uniform and high in the days following" the injection. .
The antibody levels of these people were 10 to 45 times higher than those who had not been previously infected, according to the scientists, who took samples at regular intervals.
No difference in antibody levels
After the second dose, antibody levels among people who had previously had the disease were still six times higher on average than in others.
But, write the researchers, "no increase in antibody titers was observed in former Covid-19 patients who received the second dose", which therefore had a very limited effect for them.
No notable difference between the levels of antibodies produced by either of the two vaccines, Pfizer or Moderna, was also observed.
The scientists also looked to see if the side effects differed between people who were cured and people who had never been infected, in a group of 230 participants this time.
People who had already developed natural immunity after their infection with the virus were found to have mild side effects more often after their vaccination (fever, fatigue, chills, headache or muscle or joint pain), without any leads to hospitalization.
But the researchers warned that more studies should be conducted to confirm this trend.