Danish study finds omicron subvariant more infectious than original variant

The probability for spreading within a household was 39% for BA.2 versus 29% for BA.1.

According to a Danish study, the BA.2 subvariant of the Omicron COVID-19 variant, which has quickly taken over in Denmark, is more transmissible and capable of infecting vaccinated people than the more prevalent BA.1. People infected with the BA.2 subvariant were around 33% more likely to infect others than those infected with the BA.1 subvariant, according to the study, which looked at coronavirus infections in more than 8,500 Danish households between December and January. In both vaccinated and unvaccinated people, BA.2 is more contagious than the original BA.1 strain, although the proportionate increase in susceptibility to infection was much greater in vaccinated people than in unvaccinated people. This means the subvariant is more effective at evading vaccine protection than BA.1, which was more contagious than other variants.

"We conclude that Omicron BA.2 is inherently substantially more transmissible than BA.1, and that it also possesses immune-evasive properties that further reduce the protective effect of vaccination against infection," the study's researchers said. Researchers from Statens Serum Institut (SSI), Copenhagen University, Statistics Denmark, and Technical University of Denmark conducted the study, which has not yet been peer-reviewed. According to the World Health Organization, BA.2 had a 39% chance of spreading within a household, compared to 29% for BA.1, the initial omicron variant that was dominant worldwide. Cases of BA.2 have also been reported in the United States, Britain, Sweden, and Norway, though to a smaller extent than in Denmark, where it accounts for approximately 82% of cases.