A recent Danish study has found that the BA.2 subvariant of the Omicron coronavirus is more transmissible than BA.1 and more able to infect vaccinated people. The study, analyzed Covid infections in more than 8,500 Danish households between December and January.
The findings showed that people infected with the BA.2 subvariant were approximately 33% more likely to infect others, compared to those infected with BA.1.
The BA.2 variant has become the dominant strain in Denmark where it accounts for roughly 82% of cases, but worldwide the "original" BA.1 accounts for more than 98% of Omicron cases.
Lead study author Frederik Pleaser told Reuters, "If you have been exposed to Omicron BA.2 in your household, you have 39% probability of being infected within seven days. If you instead had been exposed to BA.1, the probability is 29%. That suggests BA.2 is around 33% more infectious than BA.1."
The study also showed that BA.2 was relatively better than BA.1 at infecting vaccinated and booster-vaccinated people, indicating greater "immune evasive properties" of the subvariant.
Researchers did not discount the vaccines, stating they still play an important role, claiming both booster-vaccinated and fully vaccinated individuals are overall less likely to get infected and transmit either of the subvariants, than the unvaccinated.
The study's researchers summarize, "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, was conducted by researchers at Statens Serum Institut (SSI), Copenhagen University, Statistics Denmark and Technical University of Denmark and has not been peer-reviewed yet.
The World Health Organization stated on February 1 that the emerging BA.2 form of the Omicron coronavirus variant does not seem to be any more severe than the original BA.1 form based on Danish data.