WHO: Omicron subvariant now dominant in 18 countries & 6 more updates

Global COVID-19 cases overall are declining, but sequences of the BA.2 omicron subvariant are rising, with the strain now dominant in 18 countries, the World Health Organization said in its Feb. 22 weekly epidemiological update.  

COVID-19 cases worldwide fell 21 percent for the week ending Feb. 20 compared to the previous week. In all, 12 million new cases were reported last week. Global deaths also fell 8 percent from the week before. 

At the same time, global prevalence of the BA.2 omicron subvariant is rising, according to the report. So far, the strain has been detected in 85 countries and is now dominant in 18. "This trend is most pronounced in the Southeast Asia region, followed by the Eastern Mediterranean, African, Western Pacific and European regions," the WHO said.

Six more updates on BA.2: 

1. As of Feb. 21, the U.S. had identified 1,359 COVID-19 cases involving BA.2, according to outbreak.info, a platform that tracks data on COVID-19 variants and is supported by the CDC and other national research groups. The strain has been identified in every state but Iowa, Maine and Oklahoma, though its overall prevalence in each state is very low, accounting for 0.38 percent or less of all samples sequenced. 

2. Initial data indicates BA.2 has a growth advantage over BA.1 — the original omicron strain —though the "difference in transmissibility appears to be much smaller" than the difference between BA.1 and delta, the WHO's SARS-CoV-2 virus evolution group said Feb. 22. The WHO said in its Feb. 15 weekly update that early evidence based on growth rates in Denmark indicate the strain is 30 percent more transmissible than BA.1.

3. There have been documented cases of reinfection with BA.2 after infection with BA.1, though early data based on population-level studies suggest that infection with BA.1 provides strong protection against reinfection from the omicron subvariant.

4. So far, real-world data from South Africa, the U.K. and Denmark have found no significant difference in disease severity between BA.2 and BA.1, the WHO's virus evolution group said. Researchers are continuing to monitor whether the efficacy of current therapeutics and vaccines are affected by the subvariant. 

5. The WHO has also said BA.2 should remain classified as an omicron sublineage rather than getting its own name, based on available data so far. 

6. Health experts in the U.S. have said the subvariant is a reminder that new virus strains will continue to emerge, though it is not cause for panic. 

"As of now, I don't think that we need to sound a global alarm. But I do think that we need to pay attention," Dan Barouch, MD, PhD, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston, told CNN.

 

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