The most contagious BA.2 omicron subvariant has become the dominant strain of COVID-19 in the United States, but international health experts are focusing more on a new hybrid variant that may be more contagious.
The XE variant is recombinant, meaning that it consists of genetic material from two other strains, BA.1, the original omicron strain, and BA.2, known as the “stealth omicron”.
According to an epidemiological update published on March 29 by the World Health Organization (WHO), XE is estimated to be 10% more transmissible than BA.2; However, the results require further confirmation.
The variant was first detected in the UK in mid-January and since then 600 cases have been reported in the country.
The UK’s Health Security Agency said it is monitoring XE along with two recombinants, XD and XF, which consist of Delta and BA.1 strains.
UK health authorities clarified in late March that “there is not enough evidence to draw conclusions about the growth advantage or other characteristics of this variant”, but they have addressed initial reports of infection.
“This recombinant, XE, has shown a variable growth rate and we cannot confirm whether it has a real growth advantage,” said Susan Hopkins, UKHSA’s chief medical advisor.
However, the recombinant variants themselves are not out of the ordinary, according to health officials.
“Recombinant variants are not an unusual event, particularly when there are many variants in circulation, many of which have been identified so far over the course of the epidemic,” Hopkins said. “As with other types of variants, most will die relatively quickly,” he added.
WHO indicated that it would “continue to closely monitor and assess the public health risks associated with the recombinant variants” and “will provide updates as more evidence becomes available”.