Omicron sub-variants BA.4 and BA.5 are circulating at low levels in several countries in South Africa and Europe, according to the World Health Organization.
The two sub-variants of the highly contagious Covid-19 strain have been found in Botswana, South Africa, Germany and Denmark, among others, Maria WH Van Kerhove, WHO’s technical guide to Covid-19, said on Thursday.
BA.4 and BA.5 don’t look more contagious or deadly than the original omicron mutation so far, but that could change when more cases are found, she added. Van Kerch stressed the need to maintain “stable” genome monitoring systems that would allow countries to track and analyze both subvariants, as well as earlier versions of omicron.
“It’s still early. “What we need to make sure is that we continue to have the ability to track, the ability to share and the ability to analyze so that we can answer questions like this,” Van Kerchow said during a WHO briefing. live on the organization’s social media platforms.
Her remarks come days after the WHO said it was tracking dozens of cases of BA.4 and BA.5, in addition to earlier versions of the omicron such as BA.1, BA.2, BA.3 and BA.1.1.
A new wave of cases
This also comes as the more contagious BA.2 sub-variant advances in several parts of the world, fueling a new wave of Covid cases following the unprecedented surge caused by the original version of the omicron, BA.1, in the winter. BA.2 is now the dominant strain worldwide. In the United States, it accounts for about 85% of sequenced new cases and is even more prevalent in the northeastern region, where it accounts for about 92% of newly sequenced cases, according to the Centers for Disease Control and Prevention.
The earliest BA.4 sample was collected in South Africa on January 10, but data show that “genome accumulation” and the geographical distribution of the subvariant are newer, according to a report from the UK Health Security Agency published last week. . As of April 8, South Africa reported 41 cases of BA.4, Denmark reported three cases, Botswana reported two, and England and Scotland reported one each.
“Although the number of common genomes is small, the apparent geographical distribution suggests that the variant is being transmitted successfully,” said a report from the UK Department of Health.
The report also says that as of April 8, there are 27 reported BA.5 sequences, all of which were reported in South Africa between February 25 and March 25. But the Botswana Ministry of Health on Monday said it had identified both BA.4 and BA. Five cases among fully vaccinated people aged 30 to 50, Reuters reported.
The WHO has begun tracking BA.4 and BA.5 as they have new mutations, “which need to be further studied to understand their impact on the potential for escape immunity,” according to Reuters.
Both subvariants have additional mutations in the spike area, part of the virus used to invade human cells, and unique mutations outside the region, according to a WHO report released Wednesday. Such mutations are linked to “potential characteristics of immune escape,” the report said.
EVs subvariant
Another sub-variant of omicron, which scientists call XE, is also circulating at low levels in a number of countries.
XE is a “recombinant” variant that occurs when someone is infected with more than one strain, which is then combined into a new variant. In the case of XE, this is a combination of the original omicron strain BA.1 and the newer BA.2, according to Van Kerch.
“We have not noticed a change in severity,” she said, which means it is no more deadly than previous strains.
However, a report from the UK Department of Health says recent data suggest that XE may be more contagious.
However, he noted that the assessment has not remained consistent as new data are being added, which means that “this cannot yet be interpreted as an assessment of the growth advantage for the recombinant”.
The earliest confirmed case of XE is dated January 19 and was found in the United Kingdom, Thailand, India, Israel and most recently in Japan. The United States has not yet reported a case of the sub-option.
The cases of the new strain have doubled in the UK, according to the latest data from the UK Health Security Agency. About 1,125 cases of HE were identified as of April 5, up from 637 cases on March 25.
Spencer Kimball and Karen Gilchrist of CNBC contributed to this report.
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