Healthcare professionals are tracking a new sub-variant of Omicron, classified as XE, a hybrid of two previously identified sub-variants. These types of “recombinant” sublines contain genetic material from two or more different viruses and are not new, but this particular one has attracted some attention due to evidence of community transmission.
Since South African scientists identified Omicron more than four months ago, a number of sub-variants have evolved, including BA.2, which is currently circulating in Canada and elsewhere in the world. Here’s what we know so far about the XE subvariant:
WHAT IS SUBJECT XE?
XE is a recombinant of BA.1, which drives Canada’s fifth wave during the winter holidays and throughout January, and BA.2, which feeds the current sixth wave. There were 1,125 cases of XE in England as of April 5, representing less than one percent of the total sequences, according to a technical briefing issued by the United Kingdom’s Health Security Agency (UKHSA) on April 8.
In addition to the mutations in BA.1 and BA.2, XE also contains three mutations that are not present in all sequences for BA.1 and BA.2, according to the United Kingdom report.
HOW COMMON ARE RECOMBINANT OPTIONS?
“Recombinant variants are not uncommon, especially when there are several variants in circulation,” Dr Susan Hopkins, UKHSA’s chief medical adviser, said in a statement on March 25.
“Several have been identified in the course of the pandemic so far. As with other types of options, most will die relatively quickly.
The United Kingdom has previously identified other recombinants, including XD and XF, which are recombinants of Delta and Omicron BA.1.
HOW TRANSMITTING IS IT?
The technical director of the World Health Organization, Dr. Maria Van Kerkhove, said in a video with questions and answers that XE seems to have about a 10 percent increase in transmittance, based on early analysis of available sequences. However, Van Kerkhove said reports describing him as 10 times more portable were incorrect.
The UK Health Agency said it had an average growth rate of 12.6% per week above BA.2, but noted that over the past three weeks the growth rate has increased to 20.9%.
The WHO classifies XE as Omicron, which is a concern. The agency added that sub-variants and recombinant forms should be monitored as separate lines by public health authorities.
The Public Health Agency of Canada (PHAC) says it is actively monitoring variants of COVID-19 and evaluating new Omciron sublines and recombinants such as XE.
“Scientists are looking for signs that XE changes the severity of the disease, its transmissibility or affects the effectiveness of diagnostic tests, vaccines or treatments for COVID-19,” spokesman Mark Johnson told CTVNews.ca in an email Thursday.
“While preliminary international reports show that XE has a moderately increased transmittance compared to BA.2, more data are needed to confirm this finding.”
WHERE ARE THE XE CASES IDENTIFIED?
As of April 14, a case of subline XE, collected by border surveillance on March 22, 2022, was confirmed in Canada, according to PHAC.
“PHAC had previously suspected an additional five possible XE discoveries; however, after further investigation, it was found that they are not XE, but from an indefinite line, given the current improvements, “said Johnson.
“It should be noted that there are currently several recombinants of COVID-19 that are being monitored worldwide in addition to XE, which is not surprising given the overlap of the Delta and Omicron variants, as well as the joint circulation of BA .1 and BA .2 Omicron sub-lines. “
In the UK, most cases are concentrated in the East of England, London and the South East, according to a report by the UK Health Agency, with the first case opened on 19 January.
Cases of HE have been found in India and Japan, among other countries, according to various media reports.
ARE THE VACCINES ALSO WORKING?
While scientists are still learning more about XE and other sublines, real-world research and data show that vaccines continue to offer protection against serious diseases, especially after a booster injection.
“We need to make sure that when it’s your turn to get vaccinated and get the full course of the doses you need,” said Van Kerhove of the WHO, especially those who are most vulnerable, the elderly, have major diseases and are front line workers.
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