Covid-19: cases of reinfections on the rise with the Omicron variant

Since the Omicron wave, reinfections with Covid-19 have become more frequent. Indeed, it is not uncommon to know in his entourage a person tested twice positive for the disease, more than two months apart. How is this explained?

Reinfections estimated at 417,000 cases

According to Public Health France (SPF), which took an interest in the phenomenon, the number of reinfections with Covid-19 has been estimated at almost 417,000 cases for a year. A figure which has increased significantly, because these reinfections represent since the beginning of December 2021, 3.6% of all Covid cases in France. That is four times more cases than between March and December 2021.

Indeed, over the period studied by SPF, (people infected between March 2021 and January 27, 2022), it is precisely 416,995 cases of reinfections that have been counted, including 384,375 since December 1, 2021. That is 92% of reinfections occurred since December 1.

Reinfections linked to the Omicron wave

At the beginning of December, this coincides with the start of the fifth wave of Covid in France and the arrival of the Omicron variant. The latter is known to be much more transmissible and therefore more likely to escape the immunity acquired by a first infection. The figures confirm this: in 79% of the cases of reinfections studied, a suspicion of the Omicron variant was found.

A fact that seems to be confirmed by scientific studies. Indeed, according to a study published in the New England Journal of Medicinefaced with this variant, a previous contamination only protects 56% against a new infection.

Young people and health professionals more affected

In 52% of cases, reinfections occurred among 18-40 year olds, according to Public Health France, and 6% among caregivers. Figures that can be explained by “lower vaccination coverage” among the youngest andless adherence to barrier gestures“; for the second category it is rather a “overexposure to the virus due to their professional activity” which would explain these reinfections. For Public Health France, this number of reinfections is even lower than the reality.

Often asymptomatic reinfections

Reinfections which would be underestimated because most of the time asymptomatic, further explains the report from Public Health France. In effect, “51.4% of possible cases of reinfection were asymptomatic during the 2nd episode“. Discovered fortuitously, following the performance of a screening test, these reinfections took place on average 8 months after the first infection. Does this mean that collective immunity is not possible to achieve? “No“answers Jacques Izopet, head of the virology department at the Toulouse University Hospital to our colleagues from La Dépêche. “The fact that a large number of people are in contact with the Omicron virus reinforces the level of immunization and therefore protection of the general population”.