Chances of reinfection from Omicron mutations evaluated

Danish study says it’s possible to catch the Omicron BA.2 subvariant after the “original” BA.1, but it’s uncommon

Getting infected with a subvariant of Omicron after having had the original Omicron variant is rare, according to researchers in Denmark who published their results on Tuesday. The study has yet to be peer reviewed.

The study, led by Denmark’s top infectious disease authority, the Statens Serum Institut (SSI), identified 1,739 cases of reinfection between November 21, 2021 and February 11. The positive reinfection was confirmed between 20 and 60 days prior to the first infection.

During this period, more than 1.8 million infections were registered in Denmark.

Using a smaller sample group, the researchers found only 47 instances of BA.2 infection following an initial infection with the “original” Omicron BA.1. 

“We provide evidence that Omicron BA.2 reinfections are rare but can occur relatively shortly after a BA.1 infection,” the study authors said.

The study noted that those who became reinfected tended to be young and unvaccinated. The case only caused mild disease, none of which led to hospitalizations or deaths, the researchers added.

Less viral activity was also noted during the second infection, suggesting that some form of immunity would have been gained from BA.1 infection.

The BA.2 subvariant of Omicron quickly overtook the original Omicron variant of Covid-19 in Denmark and has since spread around the world, including to the UK.

BA.2 now accounts for more than 88% of cases in Denmark and differs from the BA.1 variant by up to 40 mutations.

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