Danish scientists recently discovered a subvariant of the highly transmissible Omicron COVID variant the is inherently more contagious and may evade vaccine protections better than previous strains, according to a study published Sunday.
The new subvariant, referred to as BA.2, spread more easily across the population of Denmark regardless of an individual's sex, age, household size or vaccination status, according to the study led by a team of scientists affiliated with the University of Copenhagen, the Danish Health Ministry, and other health institutions. The study has yet to be peer reviewed.
The study also identified a second Omicron subvariant, referred to as BA.1. However, BA.2 has rapidly replaced BA.1 as the dominant subvarint in Denmark, the study notes. According to the study, the probability of an infected individual spreading either BA.2 or BA.1 to their household within seven days was 39% and 29%, respectively.
The study also found that BA.2 is more contagious that BA.1 among both vaccinated and unvaccinated people, meaning that the former subvariant is even better at evading the virus-neutralizing protection offered by current vaccines more than Omicron and its BA.1 subvariant; both of those variant strains are significantly more contagious than any other previous COVID variant.
However, viral transmission rates among unvaccinated people were higher with those infected with BA.2 compared to BA.1, meaning that unvaccinated people may be carrying a higher viral load with BA.2, the study notes. The study added that while fully vaccinated people are more likely to be infected with BA.2 than previous strains, they are less likely to spread it to others. Moreover, individuals who received a booster shot were even less likely to transmit the virus compared to those who only received two doses of vaccine.
Encouragingly, Danish scientists also noted that infection caused by BA.2 was generally milder than those caused by the Delta variant.
Dr. Maria Van Kerkhove, technical lead of COVID-19 response at the World Health Organization (WHO), said during a press conference Tuesday that there's no indication that BA.2 causes more serious infections that the original Omicron strain, but data shows it to be more transmissible.
"We need people to be aware that this virus is continuing to circulate and its continuing to evolve," Van Kerkhove said. "That's why it's really important that we take measures to reduce our exposure to this virus, whatever variant is circulating."
The WHO labeled Omicron a variant of concern back in November, and its BA.1 and BA.2 subvariants have not been separately categorized by the agency.