‘Stealth’ Omicron Sub-Variant Detected In 57 Countries, WHO Says
The mutated version of the omicron Covid variant—known as BA.2 and termed “stealth omicron” by some scientists—has been found in 57 countries, according to the World Health Organization, which said early data indicates it is more infectious than other versions of omicron.
Over the last six weeks, the BA.2 subvariant has overtaken the “original” omicron strain, BA.1, as the dominant form of the virus, according to genetic data submitted to GISAID, an open source genome repository, the WHO said.
Though BA.1 still makes up more than 96% of sequenced omicron cases, BA.2 accounts for more than half of the sequenced omicron cases in some countries, the agency said in its weekly epidemiological report.
The WHO said little is known about the differences between omicron subvariants, though early evidence indicates BA.2 is more infectious than the more common BA.1.
Maria Van Kerkhove, the WHO’s technical lead on the coronavirus pandemic, told reporters there was “no indication that there is a change in severity” with the BA.2 subvariant.
The health agency said investigations into the characteristics of BA.2—including transmissibility and its ability to escape immune defenses—should be “prioritized independently” to BA.1, stressing it is important to consider how common BA.2 is in the context of how many Covid cases there are.
Since omicron was first identified last November, several virus lineages have been identified under the omicron banner, the WHO said. The subvariants—including BA.1, BA.1.1 (often grouped with BA.1), BA.2, and BA.3—are being monitored by the agency to identify possible threats and coordinate pandemic responses. Data on BA.2’s behavior is limited, though its genetic composition could make it harder to identify, prompting the moniker “stealth omicron.”
The BA.2 omicron subvariant has been detected in countries including Denmark—where it makes up an estimated 80% of cases—the U.S., the U.K., Singapore, India and South Africa, according to Outbreak.info, a variant tracking tool using data from GISAID. The strain has also been identified in at least 29 U.S. states, according to the tracker, including Hawaii, Arizona, California and Massachusetts.
Robert Hart / forbes.com