Omicron subvariants behind South Africa surge detected in Canada
Two new Omicron subvariants that are driving a surge of COVID-19 infections in South Africa have been detected in Canada.
In an email to CTVNews.ca, a Public Health Agency of Canada (PHAC) spokesperson confirmed they are aware of three BA.4 cases in Canada, and one of BA.5.
“The Government of Canada has a strong monitoring program in place with the provinces and territories to identify COVID-19 variants in Canada, including the Omicron variant of concern and its sub-lineages,” they said. “Scientists are looking for signs that Omicron sub-lineages such as BA.4 and BA.5 change disease severity, transmissibility or impacts the effectiveness of diagnostic tests, vaccines or treatments for COVID-19.”
The latest government data shows the highly-transmissible BA.2 Omicron subvariant is currently the most common cause of COVID-19 infection in the country.
“As with all new sub-lineages of COVID-19, scientists from the Public Health Agency of Canada, along with national and international experts, are actively monitoring and evaluating the BA.4 and BA.5 sub-lineages and the associated studies,” the PHAC spokesperson said.
One early study, which has not been peer-reviewed, suggests BA.4 and BA.5 “show potential higher transmissibility over BA.2” and could also possibly evade antibodies created from previous Omicron infections.
Another study, also undergoing peer-review, suggests that although vaccination “would likely offer good protection against severe disease,” the two subvariants’ ability to dodge antibodies could “result in a new infection wave.”
That wave has already started in South Africa, where BA.4 and BA.5 were first identified.
“Subvariants are driving a major surge in cases,” World Health Organization (WHO) director-general Tedros Adhanom Ghebreyesus said during a media briefing on Tuesday. “Omicron, and specifically BA.4 and BA.5, is driving the upsurge in South Africa, while BA.2 is dominant worldwide.”
Since late April, new COVID-19 infections in South Africa have numbered in the thousands each day, up from hundreds the month prior. In a May 4 update, the WHO said there were more than 32,000 cases in the country over the previous week, an increase of 67 per cent. Less than 40 per cent of the population of 60 million is fully vaccinated.
The WHO initially announced it was tracking a few dozen BA.4 and BA.5 cases on April 11. Over the past month, the subvariants have been detected in countries such as Germany, Portugal, the United Kingdom, Austria, the U.S. and Denmark.
“The BA.4 and BA.5 subvariants were identified because South Africa is still doing the vital genetic sequencing that many other countries have stopped doing,” Ghebreyesus said earlier in May.
According to the WHO, it’s too soon to know if BA.4 and BA.5 cause more severe illness.
“It’s still very early days with this,” WHO COVID-19 technical lead Maria Van Kerkhove said in a May 3 video. “What we can say at the present time is that it is really critical that people get vaccinated. Vaccines still work incredibly well against preventing severe disease and death.”
With files from Reuters and CTVNews.ca Writer Solarina Ho