COVID-19 modelling: B.C. could soon see 2,000 cases per day if contacts don't decrease
VANCOUVER -- COVID-19 transmission in British Columbia may be beginning to slow down, but the province still has a ways to go, according to the latest modelling data presented by provincial health officials on Thursday.
The reproductive number for the coronavirus - which measures the number of new infections that can be traced to each individual who contracts it - remains above one in most regions of the province, provincial health officer Dr. Bonnie Henry said during her presentation.
A reproductive number above one means the number of cases will continue to grow, while a number below one means the number of cases will decrease, because each person who gets infected passes the virus, on average, to fewer than one other person.
The rate remains above one in Vancouver Coastal Health, Fraser Health, Island Health and Interior Health, according to data Henry presented. In Northern Health, it has dropped in recent days from just above one to just below it.
According to the provincial government's modelling, B.C. residents are currently having about 60 per cent as many "infectious contacts" as they would have had before the COVID-19 pandemic began.
B.C. residents would need to get down to 40 per cent of pre-pandemic contacts to push the "curve" of infections back down from the record highs it has hit in recent weeks, the modelling suggests.
If the province remains at its current level of contacts, cases will continue to rise, with B.C. projected to hit more than 2,000 cases per day by May.
Henry said B.C. residents have the power to avoid that scenario, pointing to the province's past success at reducing contacts and flattening the curve.
"We need to get down to 40 per cent or less and we have done that consistently," she said. "We were able to do that last March. We did that in November when we put in restrictions again."
Henry reminded British Columbians that those November restrictions are still in place, and seemed to attribute some of the recent surge in infections to "complacency" in adhering to them.
"I think we've all felt this need to have some of those social interactions again and perhaps a sense of complacency around those (restrictions)," she said. "We need to pay attention again."
"It's likely that without you or them knowing it, somebody in your community, in your connections, has COVID, may not be aware of it, and is potentially infectious," Henry added. "The more people you see, the higher that likelihood would be. … Even if we can see people outside our household, we shouldn't right now."
Part of the province's strategy for reducing contacts is the ban on indoor dining Henry imposed late last month. While it was initially scheduled to end on April 19, health officials have been indicating that it will be extended.
Data Henry presented Thursday showed significant numbers of cases and clusters happening in restaurants and other workplaces in Vancouver Coastal Health and Fraser Health over the months of February and March.
In Vancouver Coastal Health, health officials saw workplace clusters at more than 70 different restaurants, bars and lounges during those two months, according to Henry. Those clusters accounted for nearly 160 cases.
In Fraser Health, there were clusters at 50 different sites, but they accounted for more than 250 cases in total, according to the data Henry presented.
In comparison to the total number of infections B.C. recorded during the two months in question, those two figures are quite small, but Henry said they reflect a node in the social networks that drive COVID-19 transmission in the province.
As the number of young people contracting the coronavirus - whether at work or in social settings - has grown, the number of hospitalizations for people in the 40 to 59 age group has been increasing, Henry said.
That dynamic has been worsened by the increasing prevalence of variants of concern, she added.
"Before, if there were 10 people in a household, we might see transmission to two or three other people, at most," Henry said. "Now, we're seeing - with the new variants, in particular - that transmission can be widespread in households. It may be that all of the household becomes infected and it's the 40- or 50-year-old parent who ends up in hospital."
The provincial health officer maintains that relatively little COVID-19 transmission is happening in schools, however. She presented data on transmission in schools in both of the Lower Mainland health authorities.
Roughly eight per cent of COVID-19 cases in schools in Vancouver Coastal Health between Sept. 10 and Dec. 18 were connected to transmission that happened in the school setting.
Similarly, 13 per cent of cases in schools in Fraser Health between Jan. 1 and March 7 were connected to in-school transmission, Henry said.
According to the provincial health officer, this shows that transmission in schools is being driven by transmission in the broader community, rather than the other way around.