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B.C. on track for Phase 3 by mid-June, shows new COVID-19 modelling

Last Updated Jun 5, 2020 at 8:03 am PDT

Summary

In the past two weeks, Richmond has had no new cases, and 88 since the beginning of the pandemic: report

Increasing contact rates to 70 and 80 per cent of normal, however, could see cases spike in July and August

New report includes more region-specific information

VICTORIA (NEWS 1130) — New B.C. modelling data shows that people in the province must maintain a safe physical distance to prevent a second wave of COVID-19 in the fall, while revealing more specific information about the location of cases.

If people increase their physical contact rate to 50 per cent of normal from the current level of about 35, the COVID-19 transmission rate will continue to trend towards zero through August, says the report, “COVID-19 Going Forward,” prepared by the Ministry of Health.

If that rate increases to 60 per cent, cases could rise in summer.

Increasing contact rates to 70 and 80 per cent of normal, however, could see cases spike in July and August, reaching and exceeding the levels of March and April.

“If too much relaxation of modelling occurs, it may result in a rapid rebound in transmission,” says the report.

“This is what we will be watching. These show us numbers and locations of contacts. Safe contacts are what we need to keep in place — administrative and physical controls. If this continues over next two weeks, week and a half, we will be in good shape to continue with Phase 3,” Provincial Health Officer Dr. Bonnie Henry said Thursday.

“That’s what we want to stay at. We want to stay somewhere around 50 to 60 per cent. And we know that if we do that, we’re likely to have low numbers of cases over time and not to have any exponential growth in our trajectory here in B.C,” she added.

“So if our contact rate increases to 70 per cent, we are likely to see a rapid growth. And 80 per cent, we might see a rapid rebound in transmission in a very short period of time.”

Henry is concerned with clusters of cases in workplaces, specifically manufacturing plants.

Besides outbreaks in workplaces, such as food processing plants, she said some family gatherings account for a lot of other cases, including increases reported Wednesday, when there were 22.

Henry reminds workers to stay home if sick and stay distant, pointing out that since restrictions were put in place in mid-March the number of contacts the province has had to trace for each case has fallen from around 11 to a little more than three.

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“We all have the same low risk at the moment,” but health and safety measures, such as keeping contacts low and ensuring physical barriers are in place, must be maintained.

The modelling also reaffirms that children are less likely to get infected with COVID-19 than adults.

“But even if children were 100 per cent susceptible — meaning that they had the same risk as adults of acquiring the illness — opening schools will have a minimal impact on transmission in our province, as long as we continue to do the things that we’re doing,” Henry said.

Epidemiology and where COVID-19 has hit

The report further looks at epidemiology, how and where the virus has affected people in B.C.

To date, there have been 2,632 cases in the province, with 2,265 people recovered — a rate of 86 per cent.

Of active cases, 26 people remain in hospital, including six in intensive care (ICU).

With the release of the report, the province will start reporting epidemiologically linked cases — those suspected to be COVID-19, but not confirmed by a test.

Henry said there is now a consistent definition across the province of what constitutes an epi-linked case, but because of widespread testing doesn’t expect many.

She added there have only been four epi-linked cases since May 19.

The report also includes more information specific to various regions in the province, as well as the age and gender of those infected, and transmission sources.

The province will start including breakdowns beyond just regional health authority and instead report by health delivery areas.

In the past two weeks, Richmond has had no new cases, and 88 since the beginning of the pandemic until the end of May, according to the report.

Vancouver has had 13 cases since mid-May and 540 as of the end of last month.

The area south of the Fraser River has had 57 cases in the past two weeks and 523 as of May 31. The area north of the Fraser River has had 10 and 411, respectively.

The eastern area of the Fraser Valley has had 10 and 367 cases, respectively.

As of the end of May, the Okanagan had 97 cases, while cases in various areas of Vancouver Island ranged from 25 to 59.

But in the last two weeks of May, there were no new cases on the Island, according to the report, nor were there any in the furthest northern regions of B.C., or the most southeast corner.

The province, however, will still not identify specific cases by person.

Cumulative data shows a concentration of cases in the Lower Mainland, with 75 to 100 cases per 100,000 people in the Lower Mainland and only 25 cases per 100,000 in the outermost regions of the province.

“So it does tell us that as anybody who’s been watching will know that the Lower Mainland was disproportionately affected by COVID-19, with the outbreaks that we’ve had in long-term care in Vancouver Coastal in the North Shore, and in the Fraser Health region,” Henry said.

The virus continues to affect people 50 and older the most, and women in B.C. at a slightly higher rate than men.

“Men are much more likely to have more a severe illness that requires hospitalization ICU admission or to die from COVID-19,” Henry said.

The origin of the virus in B.C. has increasingly come from “European-like or eastern Canada” lineages, as well as from “China and Iran-like strains.”

“So the initial ones for us were ones that were introduced during a conference that was held in Vancouver, and we had a number of cases arise from contacting that conference, and one of the people that we knew was positive and had attended the conference had been previously in Germany during his incubation period before he became ill,” Henry said of the European-like strain.

“And so the viruses that we were seeing that came out of that conference reflected their European origin, and they were more closely related to virus sequencing that we were seeing in Germany and Italy and France.”

She added at least 87 cases in B.C. stemmed from that dental conference.

“We found three slightly different strains of a virus related to people who become sick in that attended that conference,” Henry said.

The Washington-like strain most affected the Vancouver area, while the European-like and eastern Canadian one and others affected the Fraser Valley most.

“We had an increase, a steady and rapid rise in the Washington State-like virus strains that we were detecting and that was really reflected in people coming in from Washington State, or us going back and forth across the border and bringing the virus back, and then it seeding outbreaks in our community and in our long term care homes,” she added.

‘Minimize, manage, and modify’

Deaths from the virus in B.C. have flattened and are far below those in Quebec and Ontario, as well as rates in other countries, such as Italy, Sweden, the U.S. and U.K.

“My new mantra is minimize, manage, and modify,” Henry said.

The latter, she added, could mean loosening restrictions further.

“So whether we are at work, whether we’re thinking of participating in a peaceful demonstration, we need to continue to remember: small numbers, keep our distance, and stay home, even if your symptoms are mild. No one intends to pass the virus on. But we know that when it happens, it’s those closest to us who are most at risk.”

She is not expecting a rapid increase in cases, adding health officials know now how to control the virus.

“I do not expect that we’re going to get that rapidly explosive growth that we have seen in other countries, if we continue to do things the way that we have.”

Read the full report:

COVID19 Modelling Tech Briefing_June4