Initial work, on samples taken between January 1, 2021 and January 27, 2022, showed 416,995 possible cases of reinfection for people with two positive tests at least 60 days apart. This represents 2.8% of confirmed cases during the period studied. Two categories were more affected: young adults, aged 18 to 40, and health professionals, possibly reflecting greater exposure to risk or less adoption of preventive measures.
Omicron in 79% of cases
“A very large majority of the possible cases of reinfection reported occurred during the fifth wave of Covid-19”, observed SPF, which has counted 384,375 since the beginning of December 2021. Omicron seems to be involved in 79% of the set of possible cases of reinfection, according to available and interpretable screening results. As hypotheses to explain the increase in reinfections, the agency put forward “the attenuation of the post-infectious or post-vaccination immune response that occurred over time and the impact of the Omicron variant in terms of increased transmissibility and escape immune”.
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