40 points earned in four months.
More than one in two French people had antibodies in mid-June, whether after having been infected or vaccinated, according to a seroprevalence study by Public Health France, the Institut Pasteur and ANSES, including the results were released by the health agency on Thursday evening.
This represents precisely 52.4% of the inhabitants, with a confidence interval between 49.8% and 55.7%.
In mid-February, this share was only 13.7% [12.8%;
15.3%].
To obtain such data, the scientists analyzed “tube bottoms” obtained from blood samples in the laboratory.
These are “drawn by lot by sex, by age group and by region”, while adhering to the representativeness of the population.
Thus, it is possible to detect in the blood the presence or absence of anti-SARS-CoV-2 antibodies, witnesses of an immunity conferred by past contamination or by vaccination.
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This proportion of French people who are a priori protected against infection has increased in all age groups, but the change is most marked in the elderly.
Until the start of the year, young adults aged 20 to 49 were the ones who most often carried antibodies in their bodies (more than 8% in October 2020 and more than 14% in February 2021).
This can be explained by one simple reason: since these young people are the most active, they are also the most likely to have been infected.
As of April 9, the Institut Pasteur estimated for its part that more than 30% of 20-49 year olds in metropolitan France had been infected.
The less protected West Indies
But with the vaccination, things turned around. Elderly populations have been given priority for immunization, starting with those aged 75 and over. Thus, antibodies were detected in mid-June in nearly 80% of the inhabitants of at least 70 years. At that time, just under 7 in 10 older people were fully immunized and almost 8 had received at least one dose. Considering that the majority of residents who had been infected in the past lost their antibodies or received a dose of vaccine in the meantime, these vaccine coverage is quite consistent with the results of the seroprevalence study.
According to a seroprevalence study by Public Health France, the Institut Pasteur and ANSES, more than one in 2 French people had anti-SARS-CoV-2 antibodies (following an infection or vaccination) mid- June.
This is 40 points more than in February (13.7%).
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- Nicolas Berrod (@nicolasberrod) September 10, 2021
The proportion of inhabitants with antibodies increased in all regions, with Île-de-France in the lead (60.1%). Conversely, Guadeloupe (30.7%) and Martinique (21.4%) bring up the rear. This is logical, since the West Indies were relatively unaffected by the epidemic until this particularly strong fourth wave during the summer, and above all because the population there is still 2 or 3 times less vaccinated than in metropolitan France. These results, which “will soon be refined by new analyzes, already suggest a significant gain in immunity in the French population, in connection with vaccination,” observes Public Health France.