In Denmark, 47 cases of double infection were monitored shortly after: they were all young, above all unvaccinated (89%) and did not have serious or different symptoms compared to the infection with BA.1. A possible but rare occurrence
The sister variant of Omicron, called BA.2 O Omicron 2, constantly increasing in the world, given its slight (but greater) ability to infect compared to the already highly transmissible version BA.1. In Denmark it took over in January.
According to WHO – which explained how BA.2 appears inherently more transmissible than BA.1 – the data appears to confirm that Omicron 1 infection provides strong protection against BA.2 reinfection.
Now for the scholars of the Statens Serum Institut Copenhagen (one of Denmark’s largest research institutes in the health sector) have published a study that examines 47 cases of BA.2 infections occurring shortly after a BA.1 infection. Although the publication is an unaudited prepress, it contains important data: We provide evidence that reinfections of Omicron BA.2 occur shortly after BA.1 infections, but they are rarethe authors write.
The study in detail
To investigate the possibility that, after taking Omicron, you could soon be reinfected with the sister variant, the scientists selected a subset of samples from 1.8 million cases of infections ranging from November 22, 2021 to February 11. 2022. Individuals with two positive samples (between 20 and 60 days between the first and second infection) were selected from this group. Out of a total of 187 such cases, 47 cases of BA.2 reinfection were identified immediately following a BA.1 infection. Of these 47 cases: 89% were not vaccinated, 6% were vaccinated twice, 4% had only one dose. The data further underlines the greater immunity obtained from the combination of vaccination / infection compared to the immunity induced by the infection alone. No one was hospitalized or died in the control period. The symptoms were basically the same between the first and second reinfection. The viral load appeared to be lower in reinfection. Most reinfections occurred in people of age less than 30 years old.
A rare possibility
In all on a very high number of positives recently registered in Denmark (32% of the population) only 0.1% have been confirmed recent reinfezioni. The reinfection rate appears to be low given the high number of positive SARS-CoV-2 tests during the study period, but nonetheless highlights the need for ongoing assessment of vaccine-induced and / or natural immunity duration. authors. An important aspect concerns the short time between the two infections: the definition of the ECDC (European Center for Disease Prevention and Control) for a reinfection of more than 60 days between the two infections: the shorter time spent for some of the cases studied by the Statens Serum Institut it could lead to a reassessment of the timing. Researchers from Israel have also identified a handful of cases in which people cured of BA.1 subsequently became infected with BA.2: on the other hand Omicron 2 not the same virusshares 38 mutations with BA.1 but has an additional 27 unique mutations (in this article
what we know so far about BA.2).
In Italy and in the world
In Italy, according to the latest monitoring dating back to the end of January, BA.2 present at 3% in Omicron-type sequences (representing 99% of all cases detected). The sister variant is more transmissible but appears to have the potential to develop severe disease similar to BA.1 (hence mild), at least in the real world. Reinfections should be limited in number and i vaccines in use are still effective
above all after the third dose and especially against hospital admissions. With regard to contagiousness, BA.2 could prolong the epidemic waves but not by much: in South Africa and Denmark, where prevalent, cases have dropped anyway.
February 23, 2022 (change February 23, 2022 | 20:18)
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