COVID-19 in B.C.: Probability of being exposed to the virus is 'much higher,' Dr. Henry warns

Elisabetta Bianchini
·5 min read
April COVID-19 modelling data update for B.C.

While British Columbia's latest COVID-19 modelling shows a "levelling off" in some key data points, Dr. Bonnie Henry, B.C.’s provincial health officer, stressed that with variants of concern spreading, people need to continue to diligently follows the public health measures in place.

April COVID-19 modelling data update for B.C.
April COVID-19 modelling data update for B.C.

"Right now the rate of infectious contacts, the contacts we are having where the virus can be transmitted others, on average in the province, is somewhere around 55 to 60 per cent," Dr. Henry said. "That is too high,...we need to get down to 40 per cent or less."

"Your probability of being exposed to somebody is higher now because we have higher rates of transmission in the community."

April COVID-19 modelling data update for B.C.
April COVID-19 modelling data update for B.C.

The effective reproductive number in B.C. has been above one across the province for a while, but some progress is being made.

"We have started to see a slowing, a bending back down of the reproductive number, which means that people are reducing those contacts that they have where the virus can be transmitted, or those infectious transmission," Dr. Henry said.

She added that a lot of movement and social gatherings occurred particularly during spring break, which led to a "rapid rise in transmission."

"That was fuelled, of course, by the fact that we have some viruses that are more easily transmitted, that are circulating [particularly] in the highly populous areas of the province."

April COVID-19 modelling data update for B.C.
April COVID-19 modelling data update for B.C.

Dr. Henry presented that COVID-19 cases saw a "dramatic increase" in the third week of March, the middle of spring break, when there were "a lot more social connections, and activity and movement of people."

But the province is starting to see a "slight blunting" of that increase, over the past week, while rates of death are also decreasing.

"What is also concerning and a lagging indicator is the increase in hospitalizations that we’ve seen in the past two weeks," Dr. Henry warned. 

April COVID-19 modelling data update for B.C.
April COVID-19 modelling data update for B.C.

In terms of COVID-19 cases being identified in the province, the Howe Sound region, which includes Whistler, has seen its average daily rate of new cases per 100,000 population fluctuate. Dr. Henry said this is particular true after increased restrictions were introduced for the area.

April COVID-19 modelling data update for B.C.
April COVID-19 modelling data update for B.C.

There have also been ongoing high rates of transmission in Surrey throughout most of the pandemic.

April COVID-19 modelling data update for B.C.
April COVID-19 modelling data update for B.C.

"As we’ve had the dramatic increase in number of cases, it's been challenging to...determine where people were exposed to COVID-19 and that gives us also an indicator of broader transmission in the community," Dr. Henry said.

She added that cases with no known link to another known case or cluster happened more commonly over the past two weeks.

April COVID-19 modelling data update for B.C.
April COVID-19 modelling data update for B.C.

B.C. is seeing a "steeper increase" in COVID-19 cases in younger age groups, including both work and social interactions.

"Before if there were 10 people in a household we might see transmission to two or three other people at most, now we’re seeing, with the new variants in particular, that transmission can be widespread in households," Dr. Henry said.

April COVID-19 modelling data update for B.C.
April COVID-19 modelling data update for B.C.

As vaccines continue to be administered with an age-based prioritization across B.C., it's already showing to be effective in terms of protection from hospitalizations and deaths in older British Columbians.

April COVID-19 modelling data update for B.C.
April COVID-19 modelling data update for B.C.

In terms of hospitalizations, there has been a particular increase in people in the 40 to 59 age group admitted to hospitals in recent weeks. There has also been a rise in the number of people between the ages of 60 to 79 who have been hospitalized.

April COVID-19 modelling data update for B.C.
April COVID-19 modelling data update for B.C.

"We’ve seen a levelling off at a pretty steady rate of people over age 80 and while we have seen a slight increase in the people 18 to 39 who need hospitalization, the rates in that group remain relatively low," Dr. Henry said. "Hospitalization is now being driven by people between the ages of 40 and 79 and that’s why it is so important that we continue to focus our age-based immunization program on those down to age 40 in particular."

April COVID-19 modelling data update for B.C.
April COVID-19 modelling data update for B.C.

Dr. Henry also stressed that there has been a "relatively low infection rate" amongst school-aged children, relative to their proportion of the population.

April COVID-19 modelling data update for B.C.
April COVID-19 modelling data update for B.C.

This is particularly true for the ages five to 12 category, which is still underrepresented compared to their proportion of the population, while those between the ages of 13 and 19 have caught up to their percent of the population.

April COVID-19 modelling data for B.C.
April COVID-19 modelling data for B.C.

Case investigations, contact tracing, and outbreak and cluster investigations are conducted for exposure events in schools in B.C. The finding from the Vancouver Coastal Health region found that less than one per cent of staff and students who participated in in-person learning were infected with COVID-19 between September and December. 

The data revealed that most cases of COVID-19 in students and staff are acquired in their household or in the community.