COVID News: Omicron Subvariant Becomes Dominant in Ontario

A new subvariant of Omicron is expected to become the dominant strain of COVID-19 in Ontario, health officials say.

According to the latest epidemiological summary from Public Health Ontario (PHO), the BA.5 subvariant has « the fastest comparative growth rate of any lineage in Ontario. »

The proportion of BA.5s in sampled positive cases rose from 3.1% to 6.7% between the last week of May and the first week of June, officials found. The weekly growth rate is also 3.22 times that of the BA.2 sub-variant over the past 12 weeks.

“Based on this European data, and other data as well as this, it appears to be more transmissible than the BA.2 variant,” Dr. Samir Patel, head of microbiology and laboratory sciences, said on Monday. at PHO, at CTV News Toronto.

By the end of the month, Patel predicts that just over 50% of all COVID-19 cases in the province will be the BA.5 subvariant.

« It’s also consistent with what we’re seeing internationally, » he added.

Omicron’s BA.5 subvariant has fueled an increase in cases in the United States as well as several European countries. Last week, Canada’s Chief Public Health Officer, Dr. Theresa Tam, noted that BA.5 accounts for about 6.5% of COVID-19 cases in Canada.

Patel says health officials don’t have enough information to say whether the BA.5 subvariant is more serious than the others, but they are « keeping an eye on it. »

« It’s more transmissible, so we’re seeing BA.5 infection in people who have had their full dose of vaccination … but we’re not seeing serious disease either, » Patel said. « We need more data to be able to say conclusively that, yes, you know, vaccinated people can get infected, but the hospitalization rate or the severity is going to be low. »

Patel added that officials still recommend getting vaccinated against the new coronavirus because it will likely provide some protection against hospitalization, regardless of the subvariant. This was echoed in new data provided by researchers at Beth Israel Deaconess Medical Center, who found that the new subvariants are more likely to evade antibodies.

« These data show that subvariants BA.2.12.1, BA.4, and BA.5 substantially escape neutralizing antibodies induced by both vaccination and infection, » the researchers wrote in the New England Journal of Medical.

According to PHO data as of June 17, just over 18% of patients hospitalized with at least two doses of the COVID-19 vaccine were linked to the BA.5 subvariant. Patel argues that this statistic is not concerning because the more a variant spreads, the more likely it is to naturally infect more people, regardless of vaccination status.

« We all need to get vaccinated, » he said. « If you are eligible for the third booster, you should get vaccinated…(if) you are eligible for the fourth booster, you should also get vaccinated. »

It is not yet clear how the emergence of a new dominant strain will impact the overall number of COVID-19 cases in Ontario or the province’s health care system, but according to data provided by the Scientific Advisory Table , it seems that the concentration of the new coronavirus in wastewater is starting to slowly increase.

Most areas, with the exception of Southwest Public Health Units, are seeing an increase in the concentration of COVID-19 in sewage signals.

Just a month ago, public health officials noted an increase in BA.2.20 subvariants in Ontario.