There are nearly a million possible reinfections in France, with the outbreak of contamination linked to the Omicron variant, Public Health France said on Friday. “The results obtained on the samples between March 2, 2021 and April 24, 2022 show 961,550 possible cases of reinfection identified, including 96.7% since December 6, 2021”, according to the health agency.
The 18 – 40 year olds in the most affected
Two categories were more affected: adults aged 18 to 40, and health professionals. This is the possible reflection of greater exposure to risk, less adoption of preventive measures or lower vaccination coverage. Women were slightly more reinfected than men.
The overwhelming majority of second episodes occurred during the fifth wave of the pandemic. The highly contagious Omicron variant is involved in almost all possible reinfections (nearly 93%), according to available and interpretable screening results.
Decreased immune protection
The rebound in the circulation of Sars-Cov-2 in the spring and the emergence of the Omicron BA.2 sub-lineage, which is more transmissible than BA.1 and has become the majority, are “two factors that may play a role in the current trend to the increase in the number of reinfections”.
“It also seems more likely that the decrease in post-infectious or post-vaccination immune protection over time in the French population amplifies this phenomenon,” writes SPF.
Results to be tempered
The average time between the two episodes of infection is just over seven months. Public Health France recalled the limits on its assessments of reinfections, for lack of clinical, virological or epidemiological data.
In view of the description of cases of early reinfections in the world, the French agency also questioned a reduction to 30 days of the period taken into account between two episodes of Covid-19.
But “the analysis of possible reinfections occurring between 30 and 59 days shows that it is difficult to take them into account”. “The most likely are cases of prolonged infection rather than cases of reinfection,” SPF said.
