(Reuters) –the U.S. Centers for Disease Control and Prevention has said.
Scientists are tracking a rise in cases caused by BA.2, now the dominant variant in South Africa, which is spreading rapidly in parts of Asia and Europe.
The World Health Organization said in February that the BA.2 lineage of Omicron appears to be more transmissible than the original BA.1 version, based on initial data. Africa’s top public health body in February said BA.2 does not cause more severe disease than BA.1.
U.S. daily cases have started to decline in recent weeks after touching record levels in January, with the CDC dramatically easing its COVID-19 guidelines for masks, including in schools.
Among other versions of Omicron that have been circulating since December, BA.1.1, a descendant of BA.1 with one additional mutation, makes up around 73.7% of U.S. samples.
Largely displaced by BA.1.1, the BA.1 version of Omicron as well as another sublineage known as BA.3 are grouped together by the CDC as B.1.1.529 and make up 14.7% of the genomic surveillance samples.
The CDC estimates that BA.2 made up 6.6% of cases, revised down from 8%, of circulating variants in the country the previous week.
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