The essentials In Catalonia, scientists claim to have detected a case of recontamination that was only 20 days between two infections. Researchers are asking about the immunity of an initial infection and vaccination.
It is a phenomenon observed with great concern by scientists: that of recontaminations with Covid-19. At a time when the particularly contagious BA.2 variant accounts for 96% of infections, the question of protection through infection with the virus and through vaccination arises. What raises questions is the case of a 31-year-old woman who contracted the virus again in Spain just 20 days after an initial infection. This is the shortest time between two infections ever observed since the pandemic began.
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This medical case, which will be presented at the end of April at the European Congress of Clinical Microbiology and Infectious Diseases in Portugal, was discovered last December. The young woman was first infected with the Delta variant, then three weeks later with the Omicron variant. This medical case is all the more surprising given that the 30-year-old presented a full vaccination schedule: this Spaniard had received her booster shot 12 days before testing positive for the virus in December 2021 thanks to her work’s routine swab program. The young woman was placed in solitary confinement for 10 days before returning to work in January and being contaminated again.
What protection?
“This case underscores the potential of Omicron to evade prior immunity acquired either through natural infection by other variants or through vaccines,” said Dr. Gemma Recio of the Catala Institute. In other words, we can no longer say that a person who has already been infected with Covid-19 is fully protected from being infected with the virus again, even if they have completed their vaccination schedule.
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dr However, Gemma Recio claims that previous infection or vaccination against the virus “appears to be partially protective” against developing severe forms of the disease, particularly in “individuals contaminated with Omicron”. For the Catalan scientist, this shows that it will be necessary to maintain “virus genomic surveillance in fully vaccinated subjects exposed to reinfection” in the coming months.
weakening of the immune response
In France, cases of reinfection are not uncommon. In France, a study published last March by Santé Publique France identified 685,858 possible cases of reinfection between March 2, 2021 and March 20, 2022. Reinfection cases are defined as all people with at least two positive tests recorded in the database and Lasted 60 days apart or more. According to the authorities, the average time between the two episodes of infection was 242 days.
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“It seems likely that the weakening of the immune response after infection or after vaccination in the French population plays a role in this marked increase in the frequency of possible cases of reinfection, especially in people who have not received a booster vaccine, Public Health France commented back then. It is also very likely that the very high prevalence in France of the Omicron variant, characterized by increased transmissibility and significant immune escape, amplifies this phenomenon.”