Health officials are keeping a sharp eye on the COVID-19 omicron subvariant BA.2, which appears to be more contagious than the current BA.1 strain — but its health impacts are still unclear.
A new World Health Organization study reported that even as COVID-19 cases are falling, BA.2 accounted for 21.5% of all new omicron cases analyzed worldwide in the first week of February. (Omicron cases accounted for more than 98% of sequenced samples around the globe the previous 30 days.)
BA.2 accounted for the majority of cases a week ago in 10 countries, including Denmark, India, China, Guam and the Philippines.
Southeast Asia had the highest prevalence of BA.2 (44.7%), and North and South America had the lowest (1%).
But the subvariant’s health impacts are still unknown. In some countries where BA.2 is spreading, hospitalizations are still decreasing.
A recent study in Japan using hamsters, which hasn’t yet been peer reviewed, found BA.2 was both more transmissible and more pathogenic.
Epidemiologist Eric Feigl-Ding, a senior fellow of the Federation of American Scientists, called the findings “worrisome” and said WHO should upgrade the strain to a “variant of concern.”
But critics cautioned that animal studies are difficult to translate to humans and that so far the increasing number of BA.2 cases doesn’t appear to be boosting serious health effects.
Jeremy Kamil, associate professor of microbiology and immunology at Louisiana State University Health Shreveport, pointed out to Newsweek that the real test is happening in the world’s population and evidently “disease severity is considerably less than previously.”
He also noted that immunity to BA.1 will “mitigate against, and in most cases fully protect, people from BA.2 infection in the near term.”
Tom Peacock, a researcher in the Department of Infectious Diseases at London’s Imperial College, also predicted that any “increased severity” in BA.2 over BA.1 will be “modest.”
“If we were re-approaching Delta levels of severity again it would have been clear for a while now,” he said in a tweet.