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Omicron's spread in B.C.: How much and how fast

Public health labs can't sequence Omicron fast enough to provide real-time data; but it is assumed by officials the new COVID-19 variant will represent nearly all cases in the very near future

The B.C. Centre for Disease Control is sequencing every positive COVID-19 case to determine the rate of Omicron’s spread in the province.

So far, the results are unsurprising: it’s spreading fast.

However, the exact number of cases of the latest variant in British Columbia is delayed by as much as seven to 11 days, as that’s how long the centre takes to sequence each specimen.

“There is a bit of a delay … the whole genome sequencing takes several days,” explained provincial health officer Dr. Bonnie Henry at her most recent press conference on Dec. 17.

“That's one of the challenges we're facing with this new variant around the world, is it takes time before you know when you can look back and look at what are we seeing,” said Henry.

On Dec. 17, the Ministry of Health announced 167 new “identified” cases of the COVID-19-causing variant that is showing significant resistance to the vaccines — particularly in terms of spreading the virus and presenting mild cold and flu symptoms. That’s more than double the total cases identified on Dec. 16: 135.

Henry announced the first case of the variant on Nov. 30. Omicron was first detected in South Africa, in a traveller from Nigeria.

The centre released its latest weekly Variant of Concern (VOC) report on Dec.17, which shows Omicron starting to gain traction on its rise to become the dominant variant, taking over from the Delta variant. However, the data is only complete to Dec. 4, so it provides little real-time context for the rapidly moving situation.

Typically, only a random sample of tests is used to find variants; however, the VOC report states: “To address the new Omicron …sequencing of all positives samples has resumed with retrospective specimens collected from November 15th 2021 onwards.”

To Dec. 4, the centre’s Public Health Laboratory (PHL) had performed sequencing on 103,605 positive specimens. Sequencing is used to investigate possible COVID-19 re-infections, track variants of concern and monitor vaccine effectiveness, according to the centre.

“The PHL’s COVID-19 genomics strategy acts like the proverbial canary in a coal mine, serving as an early warning signal that informs the laboratory and public health response. The increase in cases of the P.1 and B.1.1.7 variants in B.C. led to a change in the laboratory testing strategy to more rapidly identify and target outbreaks associated with variants of concern.”

However, the regular person will not be privy to what variant they have caught, according to a ministry spokesperson.

Where is Omicron spreading in B.C.?

According to the report, Omicron is spreading most extensively in the west side of the Lower Mainland (Vancouver Coastal Health) and on Vancouver Island. This fact aligns with the rapid rise in cases in both areas, Henry noted. Ninety-three of the 167 new Omicron cases announced Friday are in the Vancouver Coastal Health region.

“And as we have noted, [Omicron] has started causing a rapid increase in the number of new cases of COVID-19 that we're seeing particularly in Vancouver Coastal and the Fraser Health region and here on Vancouver Island. It is moving quickly,” confirmed Henry.

Without real-time data, Henry said data from other jurisdictions as well as rising cases among vaccinated people is evidence enough of Omicron’s rise.  

“We know from Ontario, where they’ve been ahead of us, or from the U.K., that the reproductive number, when it's introduced into the population, is higher than what we're seeing with Delta over the last few weeks,” said Henry.

From Dec. 3 to 9, fully vaccinated people accounted for 45.1% of all 2,429 new cases in B.C. whereas from Dec. 9 to 15, fully vaccinated accounted for 57.2% of the 3,394 new cases. It is assumed, for now, the increases are a result of Omicron.

Notably, in this time, hospitalizations for fully vaccinated people remain stable: 1.1 for every 100,000 vaccinated people compared to 23.8 per 100,000 unvaccinated people.

While double doses of mRNA or viral vector vaccine are providing little relief to infections, pharmaceutical companies say a third shot, which is common for many established vaccines, can prove more effective.

Henry is delaying mass booster shots for all B.C. residents until January.

The province's top doctor is also keeping most public spaces open with the exception of gatherings over 1,000 people, which must reduce their capacity by 50%.

She cited “unstructured social gatherings” as the main culprit for Omicron’s spread and has now ordered households to limit guests to a maximum of 10 people.

Henry’s also ordered clubs and restaurants to enforce a no table-hopping (mingling) rule as well as barring dancing. All organized sports tournaments are also cancelled but recreation leagues and gyms remain open. All venues require a vaccine passport.

gwood@glaciermedia.ca