Health officials are closely monitoring the omicron COVID-19 subvariant BA.2, which appears to be more contagious than the current BA.1 strain – but its health effects are still unclear.
A new study from the World Health Organization reported that even though COVID-19 cases are declining, BA.2 accounted for 21.5% of all new omicron cases analyzed globally during the past first week of February. (Omicron cases accounted for more than 98% of samples sequenced worldwide in 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 health impacts of the sub-variant are still unknown. In some countries where BA.2 is spreading, hospitalizations continue to decline.
A recent study in Japan using hamsters, which has yet to be peer reviewed, found BA.2 to be both more transmissible and more pathogenic.
Epidemiologist Eric Feigl-Ding, a senior scientist with the Federation of American Scientists, called the “worrying” conclusions and said the WHO should upgrade the strain to a “variant of concern”.
But critics have warned that animal studies are difficult to translate to humans, and so far the growing number of BA.2 cases does not appear to be increasing 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 global population and obviously “the severity of the disease is considerably less than before.” .
He also noted that immunity to BA.1 “will attenuate and in most cases fully protect people against BA.2 infection in the short term.”
Tom Peacock, a researcher in the Department of Infectious Diseases at Imperial College London, also predicted that any “increased severity” of BA.2 compared to BA.1 will be “modest”.
“If we were approaching Delta severity levels again, it would have been clear for a while now,” he said in a tweet.