Question: “What is the XBB.1.5 COVID variant? And do I need to worry about it?”
Answer: XBB.1.5, referred to by some as the Kraken variant, is just the latest in a constantly evolving string of new variants of SARS-CoV-2, the virus that causes COVID-19.
And, in particular, it’s a subvariant of Omicron, which first emerged over a year ago and soon swept around the world.
XBB.1.5 now seems to be spreading with remarkable speed in the United States.
“It was first detected in October and by the end of December it accounted for 40 per cent of all new cases in the U.S.,” said Dr. Fahad Razak, an internal medicine physician at St. Michael’s Hospital in Toronto.
“And in some parts of the United States it is even more prevalent. In the northeast, for example, XBB.1.5 represents 75 per cent of cases,” added Dr. Razak, who is also a professor in the Temerty Faculty of Medicine at the University of Toronto.
This essentially means that it has acquired certain mutations that give it an added advantage in infecting people so it is outcompeting other variants.
But the virus’s behaviour isn’t all that surprising, says Dawn Bowdish, a professor of medicine and a Canada Research Chair in aging and immunology at McMaster University in Hamilton.
“We should keep in mind that we have seen this before,” she said. Alpha, Delta and Omicron became the dominant variants “in a really short period of time.”
But just how quickly XBB.1.5 might spread through other countries will likely depend on local circumstances, such as the level of population immunity acquired through vaccinations and previous infections, and the willingness of people to adopt protective measures such as wearing face masks.
A big unknown is whether XBB.1.5 has the potential to cause more severe disease than earlier variants of the highly transmissible Omicron family.
Some areas of the United States are already experiencing an uptick in COVID-related hospital admissions, said Dr. Razak. “But I think we will probably have to wait a few more weeks to get a better sense of what is going on.” What’s more, it will take months before we know whether XBB.1.5 increases the risk of developing long-COVID, in which symptoms persist for an extended period of time.
Dr. Razak is optimistic that vaccines can help shield us from severe disease, which could lead to hospital stays or even death.
New bivalent COVID vaccines, introduced last fall, are designed to guard against the original version of the virus as well as Omicron variants.
“To the best of our knowledge, the bivalent vaccines continue to provide enhanced protection against Omicron-family variants, including all the way up to XBB which is a parent virus of XBB.1.5,” Dr. Razak said.
Canadian public health officials have reported that only a relatively small number of people – a few dozen or so – have been infected with XBB.1.5 in this country.
But Dr. Razak thinks the official figures don’t provide an accurate picture of the current situation.
“We have significant data lags in terms of reporting and at this time are only testing in a tiny fraction of those who are infected. It is much more likely that there are many thousands of cases in Canada.”
Still, it is hard to predict what will happen in Canada based solely on the U.S. example, Dr. Bowdish said.
“What we are seeing is that each country is experiencing waves of COVID very differently,” she explained.
“The United States is sort of the extreme where vaccinations aren’t targeted and many people are not very conducive to non-pharmaceutical interventions.”
The city-state of Singapore, on the other hand, is a jurisdiction that has been better able to handle COVID waves through a combination of health measures and public compliance.
By contrast, “Canada is in the middle of the road with regards to having the population vaccinated,” Dr. Bowdish said.
“We have terrible COVID vaccination rates for kids and we are pretty bad in the middle-aged people. But we have reasonably good rates in older adults and the most vulnerable people.”
Dr. Razak says the arrival of XBB.1.5 provides “a strong impetus” for Canadians to get a shot if their vaccine status isn’t up-to-date. “I think the appropriate response is to be cautious because we don’t yet know if it will cause severe disease.”
And protection isn’t limited to just vaccines, said Dr. Bowdish. “All the things that have been protecting us from every COVID variant to date – including masking, social distancing and good ventilation – will still help with this new variant.”
Paul Taylor is a former Patient Navigation Adviser at Sunnybrook Health Sciences Centre and former health editor of The Globe and Mail.