The public health laboratory says providing precise figures for variant cases is challenging, in part because of the delay to complete whole-genome sequencing and because not all the samples can be sequenced. (Medicago)

The public health laboratory says providing precise figures for variant cases is challenging, in part because of the delay to complete whole-genome sequencing and because not all the samples can be sequenced. (Medicago)

Variants of concern higher than reported, but giving precise data challenging: BCCDC

Director Mel Krajden attributes it to a delay to complete whole-genome sequencing and not all the samples can be sequenced

A medical director at the British Columbia Centre for Disease Control says the number of active COVID-19 cases that are variants of concern is higher than what has been publicly reported in the province.

But Mel Krajden, director of the centre’s public health laboratory, says providing precise figures for these variant cases is challenging, in part because of the delay to complete whole-genome sequencing and because not all the samples can be sequenced.

Data scientists have been calling for more timely, comprehensive information about the variants of concern in B.C. in order to help residents understand the seriousness of the threat and to persuade those who are ignoring public-health orders to follow them.

Dr. Bonnie Henry said this week that only three per cent of B.C.’s active cases are variants of concern, referring to those that have been confirmed through sequencing. Krajden acknowledged that is “not an accurate representation” of what is happening in the province.

“The numbers are high. Let’s not con ourselves. The numbers are high and they’re not going to get lower. Because this is the same trajectory that we’re following, that Alberta’s following, that Ontario’s following, so we’re not going to get out of this,” he said.

“Either that or you shut down the whole economy, and we’ve been reluctant to be so draconian.”

He said variant of concern cases are doubling about every eight to 10 days and will ultimately replace other COVID-19 strains. But he also said scientists are tracking the variants in a range of ways that go beyond just quantifying them.

“They’re looking at the trends. They’re looking at the people in hospitals. They’re looking at the severity of disease,” he said. “It’s being looked at from many, many different angles, to find: ‘What’s the right solution?’”

Experts say that B.C.’s reliance on time-consuming whole-genome sequencing is not necessary to report cases that are variants of concern. The province already quickly screens about 90 per cent of cases for a mutation that the three major variants have in common.

Ontario reports the number of presumptive variant cases every day based on this quick screening process. It then does whole-genome sequencing on some samples to distinguish between the P.1 variant first identified in Brazil and the B.1.351 variant first found in South Africa.

Health officials in B.C. have been reluctant to provide the numbers of presumptive variants of concern because some samples could end up being so-called “variants of interest” that have not been shown to be more transmissible, such as the strain first detected in Nigeria.

However, experts say that the current numbers being given only after confirmation by whole-genome sequencing are not accurate either, because B.C. does not have the capacity to sequence every case.

New data provided by the BC Centre for Disease Control gives insight, for the first time, on the number of presumptive variant cases being picked up by quick screening as part of the PCR test from January through March.

In the second week of January, there were two presumptive variant of concern cases. By the first week of February, there were 22, and by the first week of March there were 438. In the final week of March, there were 2,514, or 51 per cent of B.C.’s positive cases.

Cases confirmed through sequencing in the week of March 21 show 1,183 cases, or 21 per cent of B.C.’s positive cases. This same week, Henry told reporters that the portion of cases that were variants of concern was in the “high teens” to “early 20s.”

The centre for disease control notes that there is a weeklong delay for whole-genome sequencing. Krajden said the province has the capacity to sequence about 1,900 cases a week, though the data shows more than 2,000 cases were sequenced the week of Mar. 21.

Whole-genome sequencing for the final week of March has not yet been completed, and Krajden said the province stopped trying to sequence all variant of concern cases as of April 1.

“What we wanted to make sure is that we don’t waste our energy on confirming a U.K. variant,” he said, adding that sequencing will still be necessary to distinguish between the variants first identified in Brazil and South Africa.

“What we’re really trying to do is be as clear as possible about what’s circulating, what are the risks, are we able to detect enough variants of interest, can we do the correlations between what happens to someone who has one of these variants.”

Henry said earlier this week that the province was still sequencing all presumptive variant of concern cases. She indicated, though, that it might stop sequencing those presumed to be the B.1.1.7 variant first identified in the U.K.

The Health Ministry did not immediately respond to a request for comment.

Krajden explained that there are other challenges involved in reporting accurate numbers of variant of concern cases.

Different laboratories use different screens as part of their PCR tests, with St. Paul’s Hospital, for example, developing a screen that can distinguish between the three major variants, while others may only pick up the mutation associated with all three.

Another issue is that some samples can’t be sequenced because the amount of viral load isn’t high enough, he added.

He said he understands the public is being “driven crazy” and wants more precise data, and his centre is trying to present the information in as accurate and clear a way as possible.

But he stressed the ultimate goal was immunizing all eligible adults who want the vaccine.

“The endgame is through vaccination, converting a virus that causes severe … disease and death in predominantly the elderly into a virus that causes basically the typical common cold.”

CoronavirusHealth

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

Oregon spotted frog egg masses near Agassiz. (Fraser Valley Conservancy)
Jumping for joy over Oregon spotted frog discovery near Agassiz

Finding six egg masses could be step toward recovery of Canada’s most endangered amphibian

Sunset Manor, an assisted living facility in Chilliwack owned by the Netherlands Reformed Congregation of Chilliwack, pictured here in October 2020, had its third COVID-19 outbreak declared on April 9, 2021. (Paul Henderson/ Chilliwack Progress file)
Third outbreak declared at Chilliwack care home run by church known for opposing vaccinations

30-bed Sunset Manor owned and operated by Netherlands Reformed Congregation of Chilliwack

Peter Scherle shared this 1958 photo of his father, then-Town Chairperson Paul Scherle (centre) speaking with Queen Elizabeth II with Philip, Duke of Edinburgh, in the background. Prince Philip passed away April 9 at the age of 99. (Photo/Peter Scherle)
PHOTOS: Hope residents remember Prince Philip, royal visits to Fraser Valley

Prince Phillip died at age 99 at Windsor Castle on April 9

Sold decals on real estate signs are commonplace in the red-hot Chilliwack real estate market (THE CANADIAN PRESS/Graeme Roy)
Chilliwack homes getting offers the first day the for-sale sign goes up

The March report from the Chilliwack and District Real Estate Board shows the market remains red-hot

Fans of the Indian restaurant Shandhar Hut are excited to have a second location opening soon at the base of Promontory Road, but the project has created a financial burden for the restaurant’s owners at the worst possible time. (Chilliwack Chamber of Commerce photo)
Chilliwack businesses getting financial boost through Circuit Breaker grant

A one-time payment of $10,000 will go to restaurants, bars, breweries, gyms and fitness centres

B.C. Health Minister Adrian Dix and Premier John Horgan describe vaccine rollout at the legislature, March 29, 2021. (B.C. government)
1,262 more COVID-19 infections in B.C. Friday, 9,574 active cases

Province’s mass vaccination reaches one million people

British Columbia Attorney General David Eby. (Photo: THE CANADIAN PRESS/Darryl Dyck)
Attorney General covers housing, homelessness and justice reform in Surrey Zoom

‘I think it would be really great to hold some sessions in Surrey,’ Eby says of legislative assembly

(File photo)
Youths confront man seen masturbating while walking his dog

Police say it happened Thursday (April 8) on walking path in Surrey

Cannabis bought in British Columbia (Ashley Wadhwani/Black Press Media)
Is it time to start thinking about greener ways to package cannabis?

Packaging suppliers are still figuring eco-friendly and affordable packaging options that fit the mandates of Cannabis Regulations

Robinson Russ, 37, was fatally stabbed on April 4, according to a statement from police. THE CANADIAN PRESS/Darryl Dyck
Vancouver police name victim following city’s fourth homicide of 2021

Robinson Russ, 37, was fatally stabbed Sunday in the Downtown Eastside

A man wears a face mask past the emergency department of the Vancouver General Hospital. (THE CANADIAN PRESS/Jonathan Hayward)
Calls for stricter action in B.C. as COVID-19 variants projected to climb

Jens von Bergmann says the province has taken a ‘wait and see’ approach when early action is needed

Vancouver’s park board general manager issued a new order Friday restricting tents and other temporary structures from being set up in Strathcona Park after April 30, 2021. THE CANADIAN PRESS/Jonathan Hayward
Vancouver park board issues order to restrict tents in Strathcona Park

The order issued Friday restricted tents and other temporary structures from being set up after April 30

Vancouver Canucks general manager Jim Benning says the players who’ve tested positive for COVID-19 are recovering and the team still intends to play a 56-game season. THE CANADIAN PRESS/Darryl Dyck
Canucks players ‘mostly on the other side’ of COVID outbreak: general manager

The athletes have had a “whole range” of COVID-19 symptoms, said team physician Dr. Jim Bovard, but no one has needed to be hospitalized

Most Read