Canada has 6 confirmed cases of XE. Here’s what we know about the hybrid COVID strain

The World Health Organization is monitoring the new recombinant variant XE, first detected in the UK and now found in other countries including Canada.

Thestar.com
April 14, 2022
Ivy Mark

Canada has confirmed six cases of XE, Health Canada confirms.

First detected in the U.K., XE, the latest version of Omicron, is said to be the most transmissible variant yet, according to the World Health Organization. It is estimated to spread more easily than BA. 2, which was found to be more transmissible than original Omicron variant.

While the number of new COVID-19 cases and deaths globally appear to decline for a third consecutive week, the WHO warns this decrease “should be interpreted with caution as several countries are progressively changing their COVID-19 testing strategies, resulting in lower overall numbers of tests performed and consequently lower numbers of cases detected.”

Despite public health messaging by Canadian provinces in lifting pandemic restrictions, like mask mandates and capacity limits especially indoors in crowded spaces like schools, it still feels like COVID is everywhere.

So what do we know about XE?

What is the XE variant?

XE is a recombinant variant, which means it is a combination of genetic material from two or more different viruses. In this case, XE includes attributes of both BA. 1, the original Omicron strain, and BA.2.

The strain is now dominant in at least 68 countries, including the United States and makes up about 94 per cent of sequenced Omicron cases submitted to an international coronavirus database.

Early estimates show that the XE strain is 10 per cent more transmissible than BA. 2, but the WHO warns that this finding requires further confirmation.

XE has been given a “variant under monitoring” (VUM) designation by WHO.

“The XE recombinant is being tracked as part of the Omicron variant,” said the World Health Organization in its weekly COVID-19 update on April 5. “Variants under monitoring (VUMs) are regularly assessed based on the risk posed to global public health.”

Where has XE been detected?

“As of April 6, 2022, the Public Health Agency of Canada (PHAC) is aware of six detections of the XE recombinant lineage of Omicron in Canada,” a PHAC spokesperson told the Star in an email.

Canada has a strong monitoring program in place with the provinces and territories, said the public health agency, which works to identify COVID-19 variants in Canada, including the Omicron variant of concern and its sub-lineages, as well as recombinants such as XE.

XE was first detected in the United Kingdom on Jan. 19, 2022, and approximately 600 cases have been confirmed by the end of March 2022. It currently accounts for less than 1 per cent of total sequenced cases, according to information from the UK Health Security Agency (UKHSA).

In early analyzing of growth rates for XE, researchers found that the variant was not significantly different from BA.2. However, recent data from the UKHSA up to March 16, 2022 shows XE is 9.8 per cent more transmissible than BA.2.

Mumbai’s city administration reported India’s first case of the XE variant on April 6. It was detected in a 50-year-old woman who had travelled to the city from South Africa in February, the Brihanmumbai Municipal Corporation said in a statement.

The asymptomatic patient had no comorbidities and had been quarantined after being diagnosed almost a month later in March, the BMC said.

There are reports the new variant has also been detected in China, Thailand, the United States, Ireland and Denmark.

Do current vaccines work against XE?

Thankfully, vaccines appear equally effective against both types of omicron, BA. 1 and BA.2. For both, vaccination plus a booster offers strong protection against severe illness and death.

Scientists are looking for signs that XE changes disease severity, transmissibility or impacts the effectiveness of diagnostic tests, says Canada’s public health agency, including the efficacy of vaccines or treatments for COVID-19 against this latest strain.

“While preliminary international reports have shown that XE has modestly increased transmissibility (compared to BA. 2), more data is needed to confirm this finding,” said the PHAC.

Ontario is currently offering second booster shots to eligible Canadians 60 and older.

Canada has already started rolling out the antiviral treatment Paxlovid, the first oral treatment of COVID-19.

Are there other new strains we should be aware of?

The WHO continues to monitor and study Omicron strains, including BA. 1, BA. 2 and BA.3.

The global health agency has detected strains BA. 4 and BA.5. A small number of cases of BA. 4 and BA. 5 have now been detected in a few countries, says WHO. Both have additional mutations in the spike region and “unique mutations” which could be “associated with potential immune escape characteristics.”

WHO is also monitoring circulating recombinant variants like XE, including XD and XF.

XD, a hybrid of Delta and BA. 1, has been found in France, Denmark and the Netherlands.

XF, also a hybrid of Delta and BA. 1, has been detected in the UK and Germany.

New variants will continue to appear, says the Public Health Agency of Canada.

“All viruses, including COVID-19, change over time. These changes are called mutations, and result in variants of the virus. Not all mutations are of concern. Most do not cause more severe illness,” read Health Canada’s website, adding that some variants require closer monitoring.

“We must remain vigilant and take all available measures to limit spread.”