According to a study published in the "New England Journal of Medicine", a person cured of Covid and who has received a dose of Pfizer or Moderna vaccine is protected in the same way as a patient who has had both injections, or even more. 

A person cured of Covid-19 and then receiving a first dose of the vaccine from Pfizer or Moderna is as much or even better protected than someone who has never caught the disease but received both doses of the vaccine, according to a study .

"We hope this data (...) will help shape more nuanced immunization policies," said Viviana Simon, co-author and professor of microbiology at the Icahn School of Medicine at Mount Sinai, in New York City.

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A first dose as a "reminder"

For people who have already been infected with the virus, "the first dose of vaccine acts as a booster, making the second dose unnecessary," she added.

Published in the

New England Journal of Medicine

, this study involves blood samples from 110 people, 67 of whom had not previously been infected with the virus and 43 had been.

The results showed that after the first dose, participants who had already had Covid-19 "quickly developed titers (medical term meaning concentration or level, editor's note) 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.

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.

Study participants were diagnosed with Covid between March and April 2020, and had only developed mild or moderate symptoms of the disease.

Furthermore, no significant difference between the levels of antibodies produced by either of the two vaccines, Pfizer or Moderna, was observed.

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More doses available?

Scientists also looked to see if the side effects differed between those who were cured and those 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).

But the researchers warned that more studies should be conducted to confirm this trend.

No side effects led to hospitalization.

"The two advantages of offering only one dose to people who have recovered from Covid is that it could limit the side effects experienced, and it would allow us to increase the number of doses" available, said Viviana Simon.