Noting transmissibility of 'Kraken' COVID-19 subvariant, officials again urge booster shots

One-on-one with Dr. Kieran Moore Ontario's chief medical officer of health Dr. Kieran Moore says residents need remain vigilant against the new subvariant of COVID-19.

As the first pandemic-response guidelines of the year were released in Canada, public health officials warned its "too early" to relax COVID-19 measures, noting the spread of the subvariant known as XBB.1.5, or Kraken.

At a news conference in Ottawa Friday, Chief Public Health Officer Dr. Theresa Tam said the country's health-care sector is still recovering, and while levels of influenza and RSV have returned to the seasonal norms, COVID-19 cases still fluctuate across Canada.

"For this reason, it is still important to do everything we can to prevent severe illness," Tam said.

She and Health Minister Jean-Yves Duclos used the news conference, during which they also discussed wastewater testing at major Canadian airports, as an opportunity to echo just-released advice from the National Advisory Committee on Immunization (NACI) urging the continuation of booster doses of vaccines against the disease.

The latest guidance from NACI, Tam said, includes that bivalent boosters "remain one of our best defences" against the most severe outcomes of COVID-19.

Vaccines are not 100 per cent effective, federal guidelines say, but they can impact the severity of illness, including whether hospitalization is necessary.

While not everyone experiences severe symptoms from COVID-19, they can include trouble breathing, persistent pain and pressure in the chest, confusion, inability to wake up or stay awake, and pale grey- or blue-coloured skin, lips and nails, according to a Health Canada. Anyone experiencing these should call 911.

More common symptoms of COVID-19, including of the Kraken subvariant, include sore throat, runny nose, sneezing, cough, shortness of breath, fever, chills, fatigue, body aches, loss of smell or taste, headache, diarrhea and vomiting.

NACI'S FIRST REPORT OF 2023

Ahead of the news conference, NACI released updated guidelines – its first of the new year – on how it proposes to manage the spread of COVID-19 through 2023.

Its "initial considerations" revolve around booster shots and are "based on current evidence, vaccine principles and NACI expert opinion."

The report suggests what is top of mind for those on the committee is the uncertainty of the future of the pandemic, including how many more booster shots could be advised, and when.

NACI advised its guidance is likely to change as it monitors COVID-19 activity.

For now, its advice is the same as given in the fall: those who didn't get a booster shot in the fall, despite recommendations at the time, should do so now. As in the fall months, a bivalent Omicron-containing vaccine is preferred for everyone aged five and older in Canada, NACI's guidelines say.

Booster doses should be at least six months from an infection or previous dose, the committee said, and children between the ages of five and 11 should still only get one shot after their primary series.

In determining its guidelines, NACI noted age is still the greatest risk factor for severe outcomes from infections.

'KRAKEN' SUBVARIANT

NACI also monitors national and international data, including what Tam called "contextual information, like the level of immunity in the population," as well as the impact of different variants as they spread.

"We are seeing an increase in the proportion of sequence detections associated with the XBB.1.5 variant," she said.

Nicknamed Kraken because of its ability to spread quickly, this variant is an indication not only that COVID-19 continues to evolve, but there is a need for vaccine equity globally to prevent further evolutions, according to infectious disease researchers.

"Through whole genome sequencing of clinical specimens, XBB.1.5 is known to have been circulating in Canada at 2.5 per cent during the week of Dec. 25 to Jan. 2," Tam said.

"This proportion is projected to rise at approximately seven per cent by mid-January. While XBB variants are expected to increase in Canada, it is not known whether they will become the dominant lineage."

In an interview with CTV News, Dr. Fahad Razak, former head on Ontario Science Table, addressed what he described as exponential cases of the XBB.1.5 subvariant.

"We've seen a surge that occurred in the United States over the course of December. The estimates from the Centers for Disease Control is that it rose to about 40 per cent of all cases overall – from essentially not being present at the start of the month to as high as 75 per cent of cases in the northeastern part of the United States," he said.

"There's 10 cases here, but given how porous our border is, and the fact that we've seen these variants flood across during every wave, when he was a matter of time, we're seeing that take off occur in Ontario now."

And, he added, in areas seeing an increase in this variant, health officials are seeing a rise in hospitalizations due to COVID-19. He said some parts of the U.S. are seeing a rising death toll as well.

"We know that this could still make people very sick, especially if you're vulnerable or if you're underprotected," Razak said.

Tam said in Canada, the subvariant has not been tied with increased severity, but those studying Kraken, including infectious disease specialists at Yale Medicine, say it appears to be the most transmissible, as well as more efficient and contagious.

"Like winter weather, it can be difficult to predict exactly what we're going to see next, but we do know it's too early to put away our winter coats and boots. Similarly, it's still too early to start taking (away) the personal protective measures that have helped us weather the COVID-19 storm," she said.

WASTEWATER TESTING AT AIRPORTS

Duclos mentioned further measures related to travel to Canada from China, first announced earlier this month, that include denial of entry to all passengers arriving from China, Hong Kong and Macau who do not have a negative COVID-19 test.

Those who are permitted to enter the country, including travellers who've passed through those destinations within 10 days, are given additional information from Canadian public health officials.

Citing a "limited amount of epidemiological and genomic sequence data testing" regarding a recent surge in cases, Duclos spoke about a previously announced action that will be taken to get a sense of the spread of COVID-19.

Pilot projects at two major airports – in Vancouver and Toronto – will see the testing of wastewater from flights originating from China and Hong Kong. These projects are expected to launch at the end of the month.

"This will further enhance our ability to track the emergence of variants coming into Canada," he said.

"Wastewater monitoring is a key tool for public health surveillance. It can alert public health officials to where diseases like COVID-19 and new variants of concern may be spreading."

Wastewater monitoring is currently being used across Canada to monitor the spread here as well.

With files from CTVNews.ca's senior digital parliamentary reporter Rachel Aiello