BC COVID-19 curve is slowly starting to decrease: Henry

Feb 5 2021, 10:44 am

Health officials in British Columbia shared their most recent epidemiological modelling on Friday morning.

The announcement was given by Provincial Health Officer Dr. Bonnie Henry and Health Minister Adrian Dix. One of the most positive findings is that BC’s infection rate appears to be decreasing, although there’s still a risk that new cases could increase rapidly.

“We have now seen since December a steady decrease in our cases and transmission over time,” says Henry.

Dynamic compartmental modelling shows that the transmission rate in all regional health authorities is “relatively stable or declining,” although it remains close to 1.

The Rt estimates the average number of people that would be infected for every new test-positive case of COVID-19.

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Dynamic compartmental modelling showing the transmission rate of COVID-19 across the province (Ministry of Health)

Even the Fraser Health Authority, which was considered a COVID-19 hotspot for a significant period of time, is showing a transmission rate of just under 1. Transmission concerns in Vancouver Coastal Health, such as the ongoing COVID-19 transmission in Whistler, have resulted in an Rrate hovering around 1.

There has been, however, ongoing transmission in areas of BC that have not been heavily affected previously, such as the north and the Interior.

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Compartmental modelling showing COVID-19 transmission rates in regional health authorities (Ministry of Health)

Henry stresses that while we’re on a good trajectory, it could change quickly and we could see a very rapid spike, similar to what has been seen in other countries.

COVID-19 transmission and infection in schools

Health officials also say there remains a relatively low infection rate of COVID-19 among school-aged children. A total of 7,654 coronavirus cases were detected in British Columbians between the age of 0 and 18 years, making up 12.5% of the province’s cases from August 2020 to January 2021.

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A quantitative breakdown of COVID-19 cases among school-aged children, compared to those over the age of 19 (Ministry of Health)

Additionally, data from epidemiological modelling suggests that the reopening of schools in September did not lead to an increase in community transmission of the virus.

“School-aged children are less likely to be infected, less likely to get sick from COVID-19,” says Henry. “And we see a decrease in cases once school is starting and reflecting, really, transmission in our community.”

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The provincial government’s data suggests that the start of school has not resulted in a significant increase in community transmission (Ministry of Health).

Modelling also estimates that the infectious contact rate of British Columbians is at approximately 50% of normal.

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Dynamic compartmental modelling scenarios (Ministry of Health)

Cases will continue to decline throughout February and March should people continue to keep their contact rates low, but a spike in cases could be seen if contact rates increase.

Different variants of COVID-19 in BC

Henry also addressed the different variants of COVID-19 both in BC and around the world, describing them as “variants of concern.”

She explained that the UK strain of the virus, for example, can “take over or spread” faster than the average infection.

“Every time it replicates, there’s a potential for a mutation or a change to happen,” she says. “Sometimes the genetic code can misspell and get it wrong, and that can in some cases, lead to a virus that has some sort of ability to take over or spread faster.”

“This is one of the things that we’ve seen in the UK — the virus variant that was detected meant that it could be transmitted more easily to others.”

There’s been data in the past few weeks suggesting that variants can cause more severe illness, although Henry stresses that it can be difficult to tease apart — since more people being infected will lead to more individuals with severe illness. There’s also some concern that some vaccines may not be as effective on the variant from South Africa.

“We are doing whole-genome sequencing to look for the variants of concern that have been identified internationally. There are many other variants out there… it changes about two mutations per month. These ones are a concern because they have increased transmissibility.”

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