The World Health Organization says that the subvariants BA.4 and BA.5 are low in several countries.
Maria Van Kerkhove, WHO's technical lead on Covid-19, said Thursday that the two subvariants of the strain have been found in several countries.
As more cases are detected, the original omicron mutation could be more deadly than BA.4 and BA.5. Van Kerkhove emphasized the need to keep the genome surveillance systems that allow countries to track and analyze the two subvariants as well as earlier versions of omicron.
It is early days. We have to make sure that we have the ability to track, the ability to share and the ability to analyze so that we can answer questions like this.
The WHO said it was tracking a few dozen cases of BA.4 and BA.5 in addition to earlier omicron variant such as BA.1, BA.2, BA.3 and BA.1.2.
It also comes as the more contagious BA.2 subvariant advances across several parts of the world, fueling a new wave of Covid cases after the unprecedented surge caused by the original omicron variant, BA.1, during the winter. The dominant strain is BA.2. In the U.S., it makes up 85% of new cases, and is even more dominant in the northeast region of the country where it makes up almost all of the new cases.
The earliest BA.4 sample was collected in South Africa on January 10. As of April 8, South Africa had reported 41 BA.4 cases, followed by Denmark with three, Botswana with two, England with one, and Scotland with one.
Although the number of total genomes is small, the apparent geographic spread suggests that the variant is successful.
There were 27 reported sequence of BA.5 as of April 8, which were all reported in South Africa between February 25 and March 25. The health ministry in Botswana said on Monday that it had identified two cases of the vaccine-preventable disease among people aged 30 to 50.
The WHO began tracking BA.4 and BA.5 because they have new mutations that need to be further studied to understand their impact on immune escape potential.
The spike region is a part of the virus that is used to invade human cells, and both subvariants have unique and additional mutations outside of that region, according to a WHO report published Wednesday. The report said that such genes are associated with potential immune escape characteristics.
A number of countries have low levels of XE.
When someone isinfecting others with more than one strain, they combine into a new variant called XE. It is a combination of the original omicron BA.1 strain and the newer BA.2 according to Van Kerkhove.
She said that it is not more deadly than earlier strains.
According to a report from the U.K.'s Health Ministry, recent data shows that XE may be more contagious.
As new data is added, the estimate has not remained consistent, meaning that it is not an estimate of growth advantage.
The earliest confirmed case of XE was in the U.K., Thailand, India, Israel and most recently Japan. The US has yet to report a case of the subvariant.
According to the latest data from the U.K. Health Security Agency, there have been nearly doubled cases of the new strain in Britain. There were 1,125 cases of XE identified as of April 5, which is up from 637 cases on March 25.
CNBC's Spencer Kimball and Karen Gilchrist contributed to the report.
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