At a time when the number of covid-19 diseases was beginning to decline in some countries, including the Czech Republic, the World Health Organization (WHO) issued a warning in a weekly epidemiological report about a new mutant variant of coronavirus called “XE”. According to previous findings, it can be 10% more contagious than all known strains.
The new variant is a recombinant strain, which means that it is of a mutated hybrid of two previous versions of omikron variants – BA.1 and BA.2 – which have spread around the world. According to the WHO, the omicron subvariant BA.2 is the currently dominant strain, which is attributed to 86% of all sequenced cases.
Coronavirus in omicron XE version
Although XE currently accounts for only a small proportion of new cases, its extremely high transmission capacity could mean that it will become the dominant strain in the near future. This variant was first detected in the UK on 19 January and has since been reported and confirmed in more than 600 samples.
Current estimates suggest a ten percent advantage in community dissemination compared to BA.2, however, this finding requires further confirmation. If “significant differences in transmission and disease characteristics, including severity” cannot be identified, XE will remain in the omicron variant category.
“This particular recombinant XE has a variable growth rate and we cannot yet confirm whether it has a real advantage.” said WHO Chief Medical Adviser Susan Hopkins. “We do not yet have enough evidence to draw conclusions about the transferability, severity or efficacy of vaccines.”
Hopkins added that it is not uncommon for recombinant variants to appear. “Especially when there are several variants in circulation, and several of them have been identified during the current pandemic. As with other variants, most of them disappear relatively quickly. “
Other variants of XF and XD
The UK Health Security Agency (UKHSA), which monitors coronavirus variants SARS-CoV-2, analyzed three recombinants called XF, XE and XD. She explained that XD and XF are a combination of the older delta and the still current omicron BA.1, while XE combines the omicron in versions BA.1 and BA.2.
A recombinant variant is formed when an individual becomes infected with two or more variants simultaneously, which leads to the mixing of genetic material in the human body. Several such mutations have occurred during a pandemic in the past.
The UKHSA reports that only 38 cases of XF have been detected in the United Kingdom, but none have been reported since mid-February. There is currently no evidence of community transmission. The XD variant has not yet been identified in the United Kingdom, although 49 cases have been reported to worldwide databases.
In the United Kingdom, however, it was a total of 637 cases of XE have been confirmed so far. “The oldest of them has a sampling date of 19 January 2022. At present, there is insufficient evidence to draw conclusions about the characteristics of this variant.” stated by the Agency. However, she added that all versions are closely monitored.