"Vaccinated people have 9 times less risk of being hospitalized or dying from Covid-19 than unvaccinated people", explains to AFP the epidemiologist Mahmoud Zureik, director of the Epi-Phare structure, which associates Health Insurance (Cnam) and Medicines Agency (ANSM).
These data confirm other observations made in real life in other countries, Israel, United Kingdom or United States.
But the French study is "the largest carried out in the world", according to Professor Zureik.
Epi-Phare researchers compared the data of 11 million vaccinated people over 50 years old with those of 11 million unvaccinated people in the same age group, over a period from December 27, 2020 (start vaccination in France) on July 20.
Regarding the Delta variant, now dominant, the researchers found comparable results from the moment it gained momentum, around June 20.
"This period remains very short to assess the real impact of vaccination on this variant".
"The study must be continued to integrate data for August and September," said Professor Zureik.
This observation on the effectiveness of vaccines is valid for those of Pfizer / BioNtech, Moderna and AstraZeneca.
The study has two parts, devoted to two distinct populations. On the one hand, those aged 75 and over, with a sample of 7.2 million people (50% vaccinated and 50% non-vaccinated). On the other hand, 50-74 year olds, with a sample of 15.4 million people (50% vaccinated and 50% non-vaccinated). To compare the data, the researchers formed pairs. For each person vaccinated on a given date, they matched an unvaccinated person of the same age, same sex and living in the same region. They followed these couples until July 20 and compared hospitalization rates.
This study focuses only on the efficacy of vaccines against severe forms.
It does not allow to say to what extent they prevent being infected and transmitting Covid-19.
Other work around the world has shown that compared to other variants, Delta lowered the effectiveness of vaccines against infection.
However, avoiding serious forms is "the major public health objective", underlines Professor Zureik: "An epidemic without serious form is no longer an epidemic".
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