EG.5 subvariant may soon dominate COVID-19 cases in Canada. What to know

EG.5, the fast-spreading COVID-19 subvariant, is now circulating in Canada as health officials across the world grapple to figure out its potential impact on transmissibility, severity and vaccine effectiveness.

The World Health Organization (WHO) on Wednesday classified the EG.5 strain as a “variant of interest.” It has not been listed as a variant of interest or concern by Health Canada.

While this subvariant of Omicron has been gaining momentum in countries such as Canada, the United States, the United Kingdom, and China, prompting heightened global attention, health experts and the WHO say EG.5 does not seem to pose more of a threat to public health than other variants.

“Based on the available evidence, the public health risk posed by EG.5 is evaluated as low at the global level, aligning with the risk associated with XBB.1.16 and the other currently circulating VOIs,” the WHO stated in a release Wednesday. 

“It definitely grows at a faster rate than the other variants do,” explained Gerald Evans, chair of infectious disease in the department of medicine at Queen’s University in Kingston, Ont. “And it looks like it’s going to become by the time the fall comes around, it’s going to be the one that we are going to see most of all.”

EG.5 is a descendant of the XBB Omicron strains that have dominated viral transmission in recent months. It has the same makeup as XBB.1.9.2 but carries an extra spike mutation, Evans said.

It has a different name because when there are “too many” numbers after the XBB part, scientists will create a shorthand, like EG.5.

“They’ll only report up to three numbers after the original designation, XBB,” he said.

“But the problem is for the public is they see EG.5 and they go, ‘Oh my god, it’s a whole new variant’. It’s not. It’s actually just another evolutionary step of the known recombinant XBB strains.”

Evans called it a “subtle variation” and has shown no evidence that it will cause more severe illness or hospitalizations.

EG.5 was first reported in February 2023 by the WHO and designated as a variant under monitoring (VUM) on July 19.

Globally, there has been a steady increase in the proportion of EG.5 reported, according to the WHO.

For example, from June 19 to June 25, the global prevalence of EG.5 was 7.6 per cent, according to WHO data. And then from July 17 to July 23, it jumped to 17.4 per cent.

The largest portion of EG.5 sequences are from China (30.6 per cent), the U.S., (18.4 per cent), the Republic of Korea (14.1 per cent), Japan (11.1 per cent) and Canada (5.3 per cent).

EG.5 has been circulating in Canada since May, and its prevalent lineage — EG.5.1 — was predicted to be circulating in Canada at approximately 19 per cent between July 30 to Aug.5, the Public Health Agency of Canada (PHAC) told Global News in an email.

A second EG.5 lineage — EG.5.1.1 — was predicted to be circulating in Canada at approximately 17 per cent during the same time period. PHAC also said it was aware of 36 detections of EG.5 in municipal wastewater between May 15 to July 21.

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According to Public Health Ontario (PHO), the EG.5.1 subvariant is experiencing a weekly growth rate in Ontario that is 1.9 times higher than that of XBB.1.5, which is currently the prevailing Omicron subvariant in Canada.

In the U.S., the subvariant is now the most dominant strain., according to estimates from the U.S. Centers for Disease Control and Prevention.

“While EG.5 has shown increased prevalence, growth advantage, and immune escape properties, there have been no reported changes in disease severity to date,” the WHO said in a release Wednesday.

“However, due to its growth advantage and immune escape characteristics, EG.5 may cause a rise in case incidence and become dominant in some countries or even globally.”

It’s still too early to say if the subvariant causes different symptoms than what has been seen with Omicron, experts say.

It may be that EG.5 has similar symptoms to other versions, Dr. Shan-Lu Liu, co-director of the Viruses and Emerging Pathogens Program at Ohio State University, told NBC News on Tuesday.

These symptoms include fever, cough, fatigue, muscle aches and headache.

“Once we entered the Omicron era, the virus has changed from infecting the lungs to more infecting the upper airway,” Liu said. “But symptoms should be pretty common to the previous SARS-CoV-2 infections.”

Canadian health officials are actively monitoring and evaluating EG.5 lineages, PHAC told Global News.

“Scientists are looking for signs that EG.5 lineages would change disease severity or spread, or impact the effectiveness of diagnostic tests, vaccines or treatments for COVID-19,” a spokesperson said. “COVID-19 activity levels are currently low to moderate in all reporting provinces and territories, with most reporting stable or increasing trends.”

The concern is if the variant escapes protection Canadians have from previous vaccinations and infection (what is known as hybrid immunity), warned Dr. Prabhat Jha, epidemiologist and professor of Global Health at the University of Toronto.

This is because EG.5 is “a little bit more clever than its earlier cousins in being able to infect people,” he said.

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“In Canada, we have quite good levels of hybrid immunity. So that combination of infection and vaccination raises your immunity, so you’re protected against hospitalizations or death in a reasonable way.”

But does not necessarily protect someone against infection, Jha added.

“The worry would be if EG.5 spread enough and got enough people infected, then the elderly and those with weakened immune systems or with chronic diseases could be at risk of having to be hospitalized because of because of this strain,” he said.

However, there aren’t any signs of this yet.

In order to keep COVID-19 infections, hospitalizations, and deaths at bay, Jha said it’s important to stay up to date with vaccinations, continue regular testing, masking when possible and diligently practice preventive measures such as washing hands frequently.

Because much of the subvariant is still unknown, he said looking into the fall, it will be reasonable that there will be an uptick in COVID-19 cases.

“When schools open next month, we can expect cases to go up even more because kids will get infected and they won’t get sick or very few will get sick,” he said. “But they will transmit the virus to either parents or grandparents. And so then you have this cascade of transmission.”

Evans agreed, adding that if you are due for a COVID-19 booster, it may be time to get it soon.

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Canada’s National Advisory Committee on Immunization (NACI) released fall booster guidance last month, recommending a dose of the new formulation of the COVID-19 vaccine for the authorized age groups.

All Canadians aged five years and up should get a COVID-19 booster in the fall if it has been at least six months since their last vaccine dose or infection, whichever is later, NACI recommended.

While an Omicron-containing bivalent vaccine is currently available to Canadians, NACI said in July updated vaccine formulations may be coming in “the coming months.”

“If you’re coming up for a booster, this is to be the time to get it when those XXB variant vaccines come out next month in late September,” Evans suggested. “And if you’re really at high risk and very worried, go ahead and get your booster now.”