Once, twice, three times... Are we condemned to being contaminated by SARS-CoV-2 and its many variants?
Public Health France unveiled, this Thursday evening, a new report on people who have caught the Covid on several occasions.
A reinfection is defined as being a second contamination occurring at least two months after the previous one, each time detected by a positive test.
This has happened over 1.1 million times in total.
And this phenomenon is becoming more and more frequent.
Here's what to remember.
More and more reinfections
The curve climbs, month after month.
12% of people who tested positive during the week of June 6 to 12 had already been positive at least once in the past, in 2021 or 2022 (data for 2020 are not taken into account).
This share was close to 1% at the end of 2021, then it has constantly increased since the arrival of the Omicron variant.
This finding is not surprising, because this new strain of SARS-CoV-2 shows a strong “immune escape”.
Clearly, it manages more easily to infect people who have already had Covid and/or been vaccinated.
The vast majority of reinfections identified are also due to Omicron and its various sub-lineages (BA.1, then BA.2 and now BA.4 and BA.5).
“In view of the marked increase in the circulation of SARS-CoV-2 currently observed in France, and the characteristics of the BA.4/BA.5 sub-lineages, it is to be expected that the frequency of reinfections will continue. to increase in the coming weeks”, warns Public Health France.
Twice Omicron
12% reinfections from June 6 to 12, this corresponds to nearly 26,000 people.
And among them, almost half had tested positive for the first time since the beginning of January, that is to say when the Omicron variant became the majority.
They therefore caught Omicron twice, for example BA.1 or BA.2 then BA.5.
Ludine, 18, is in this case.
The student in the preparatory class tested positive in January and then again in mid-June.
"I was a little surprised to catch it again, because I thought the immunity was supposed to last 5 months," she says.
Read also "It's a stealth plane": what are the risks of reinfection with Covid with the new Omicron BA.5 variant?
However, we must keep in mind the very large number of people who caught Omicron during the first weeks of 2022. More than half of the people who tested positive since January 1, 2021 were tested during the first three months. 2022. It is therefore not surprising to find, in June, a fairly large proportion of people who tested positive for the first time during this period.
In the end, the risk of catching Omicron twice in a few months “remains low”, underlines Public Health France.
The older the primary infection, the greater the risk of catching Covid again.
“The individuals most at risk of infection today are those who have never had Omicron,” summarizes Prof. Olivier Schwartz, head of the Virus and Immunity Unit at the Institut Pasteur.
A more complete study to come
Public Health France warns that these data "have limitations", in particular because "they do not take into account the vaccination status of possible cases of reinfection".
A study "aiming to identify the factors associated with reinfection with SARS-CoV-2 (including vaccination status) and the severity of possible reinfections" is underway.