Two cases of delta plus variant — under close watch in the U.K. — confirmed in Alberta

Alberta has identified two cases of the delta plus variant which is being closely monitored in the United Kingdom as case numbers there grow.

While 2 cases of the delta offshoot have been documented, an Alberta expert believes there are likely more

A health-care worker collects a sample at a drive-thru COVID-19 testing facility in Alberta. (Alberta Health Services)

Alberta has identified two cases of the delta plus variant which is being closely monitored in the United Kingdom as case numbers there grow. 

Alberta Health said it doesn't have information on whether the the AY.4.2 subvariant cases are travel-related but the samples were collected in mid- to late-September.

"It's not surprising," said Dr. Stephanie Smith, an infectious disease specialist and director of infection prevention and control at the University of Alberta Hospital.  "What we anticipate will happen with this virus is it will mutate over time."

Delta plus is a sub-lineage of the delta variant containing changes to how the virus binds to cells, according to Smith.

It is not currently designated as a variant of concern by the World Health Organization.

"The evidence to date would suggest that — given that it binds a little bit more strongly to the cells of our respiratory tract —there probably is a slight increase in transmissibility," she said.

"The concern is will this over time take over the regular delta variant and be even more transmissible?"

Smith said the evidence so far suggests the increase in transmissibility is not as large as the jump between the alpha and delta variant or the wild-type and delta.

"We have seen cases in the U.K and that has been increasing. And we've now found it in 44 other countries which would suggest that it does have some evolutionary advantage. I think we're still trying to sort that out," she said

"So is it going to create a problem? I mean certainly we may see a slight increase in transmissibility, but it doesn't seem to result in immune evasion so it does appear that the vaccines that we have are still effective against this particular variant which is really important in terms of looking at the overall impact."

Dr. Stephanie Smith, an infectious disease specialist at the University of Alberta Hospital in Edmonton. She says, while there are still many unknowns, the evidence so far shows delta plus is slightly more transmissible than delta. But the change in transmissibility is not as dramatic as the shift between alpha and delta. (CBC)

No plans to resume screening all cases

The provincial lab stopped screening all positive daily COVID-19 cases  for variants of concern early in September as case counts mounted.

It is currently screening targeted populations, including hospitalized and emergency room patients, patients involved in outbreaks, healthcare workers and recent international travellers.

According to Alberta Health Services, approximately 800 cases per week then go through full genome sequencing to look for emerging subvariants such as AY.4.2

AHS said AY.4.2 is one of 26 sublineages of the delta variant that have been identified so far in the province.

In an email to CBC News, a spokesperson for Alberta Health said the provincial lab continues to update its screening protocols to monitor the spread of variants.

"Health officials are closely monitoring all emerging evidence around all variants of concern and interest, including their transmissibility, disease severity, or other factors compared to current circulating COVID-19 strains," said spokesperson Lisa Glover.

"Vaccines have proven effective against all the COVID-19 strains to date, including the variants of concern, particularly after the second dose. We continue to encourage all Albertans to get fully vaccinated as soon as possible."

However AHS says it won't return to full screening of all COVID-19 cases, even as case counts drop in the province.

"We have no plans to resume screening all positive cases, as virtually all cases in Alberta are the delta variant. Screening positive samples from target populations is very effective for monitoring for the presence of variants and the emergence of new strains in our population," said AHS spokesperon Kerry Williamson in an email to CBC News.


Jennifer Lee


Jennifer Lee is a CBC News reporter based in Calgary. She worked at CBC Toronto, Saskatoon and Regina, before landing in Calgary in 2002. If you have a health or human interest story to share, let her know.


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