Covid-19 vaccine: will you need a second dose if you have already contracted the virus? : Current Woman The MAG

AstraZeneca, Pfizer / BioNTech, Moderna … In principle, two doses of these coronavirus vaccines should be injected into patients to ensure effective protection. But in an opinion made public on February 12, the High Authority for Health (HAS) recommended administering only a single dose of messenger RNA vaccines, in other words those of Moderna and Pfizer / BioNTech, to people who have already been infected. by the coronavirus. "The single dose of vaccine will thus play a reminder role", could we read in the document.

A recommendation now confirmed by a new study conducted by researchers at the Icahn School of Medicine at Mount Sinai, in New York (United States) and published in the New England Journal of Medicine. Both Moderna and Pfizer / BioNTech sera have been tested and scientists have concluded that a single dose of these vaccines is sufficient to protect people who have previously been infected with Covid-19.

Vaccine: more antibodies in former patients after the first dose

To find out, the study authors analyzed blood samples from 110 participants. Of these volunteers, 67 people had never contracted the virus and 43 had already been infected.

Repeated swabs were taken and the researchers found that the majority of participants who had never contracted the virus had relatively weak immune responses after the first dose. "In contrast, participants with anti-Sars-CoV-2 antibodies before the first vaccine injection quickly developed uniform and high antibody titers in the days following vaccination," can we read in the study. The term "title" means "concentration" or "level". After the first dose, the antibody levels of people who had previously contracted Covid-19 were 10 to 45 times higher than those of people who had never been infected.

After the second injection, the antibody level of people who had previously been infected was still six times higher than that of people who had never been infected. But "no increase in antibody titers was observed in Covid-19 survivors who received the second dose of vaccine", can we read in the study. "The first dose of vaccine actually acts as a booster, making the second dose unnecessary.", concludes Viviana Simon, co-author and professor of microbiology at the Icahn School of Medicine at Mount Sinai.

Vaccine against Covid-19: former patients have more side effects

As part of this work, researchers were also interested in the side effects of Moderna and Pfizer / BioNTech vaccines. To do this, they observed the reactions of 230 volunteers after the injection of the first dose of the vaccine. Of these, 148 had never contracted the virus and 82 had already been affected by Covid-19.

"Overall, the two vaccines had no side effects leading to hospitalization. A total of 159 of 230 participants (69%) who responded to the survey reported having side effects after the first dose of vaccine", can we read in the study.

People who had never contracted the virus reported fewer side effects (46%) than people who had previously been infected (89%). They have reported mild symptoms such as fatigue, headache, chills, muscle pain, fever and joint pain.

Source: Antibody Responses in Seropositive Persons after a Single Dose of SARS-CoV-2 mRNA Vaccine, New England Journal of Medicine.

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