COVID-19: B.C. hospital population drops significantly in latest update

A week after the B.C. Centre for Disease Control reported its highest number of COVID-19 hospitalizations in two months, data released Thursday shows the hospital population plummeting to its lowest level since June.

CTV News reached out to the BCCDC and the Ministry of Health to inquire about the underlying reasons for such a dramatic shift, particularly at a time when health officials have been warning about and preparing for a "fall surge" of coronavirus infections for months. 

In an email, the BCCDC said "there is no indication that there are any new issues with the data" this week. 

The number of COVID-19 patients in B.C. hospitals on Thursdays since January is shown. The data reflects the hospital population in B.C. since the province switched to a "hospital census" model. (CTV)

The decline of 97 patients from last Thursday to this one is the largest week-to-week change in B.C.'s hospitalized population since it grew by more than 100 between April 14 and April 21.

It comes as the province works to move patients who are good candidates for relocation out of hospitals and into other facilities, with the goal of making room for an anticipated surge in demand during the upcoming respiratory illness season. 

This effort is not an underlying cause of the decline in the hospital population this week, according to the BCCDC, which said it is "not aware of any practice changes that would impact the number of people currently hospitalized."

COVID-19 hospitalization numbers in B.C. reflect a "hospital census" model, and include both patients who are admitted to hospital because of COVID-19 and those who are admitted for other reasons and test positive incidentally.

Since the province began reporting hospitalizations in this way in January, there have been as many as 985 and as few as 255 people hospitalized with COVID-19 on Thursdays in B.C.

CASE COUNT HITS ALL-TIME LOW

Thursday's update also included data on new, lab-confirmed cases during the most recent epidemiological week, which was Oct. 16 to 22. According to the BCCDC, there were 534 new positive lab tests during that time. 

That figure is the lowest the BCCDC has reported for an epidemiological week since the province switched to weekly updates on COVID-19 data in early April.

The drop in reported new cases is notable, but it's unclear whether it correlates with a genuine drop in transmission.

The weekly case numbers reported by the BCCDC have been disconnected from the true scope of transmission in the province since at least late December, when B.C. dramatically narrowed its testing eligibility criteria.

Lab-based testing is only recommended in B.C. when the result will inform decisions about care, specifically, when the person being tested is at high risk of severe illness and may benefit from treatment, is pregnant, or is hospitalized. 

Everyone else in B.C. can only access rapid antigen tests, the results of which are not collected or reported by the BCCDC.

Because of this, both provincial health officials – in a recent paper – and the independent B.C. COVID-19 Modelling Group estimate that official case counts from the BCCDC are off by roughly 100-fold. 

In its email to CTV News, the BCCDC said it does not believe the low number of new cases reported this week is attributable to a decrease in testing.

"COVID-19 test positivity has remained relatively stable in recent weeks," the agency said. "According to the most recent data, COVID-19 is relatively stable across multiple indicators at the moment."

The BCCDC's weekly situation report shows roughly the same number of provincially funded, lab-based tests being performed in each of the last nine weeks, though data from the most recent epidemiological week has not yet been released. 

Sarah Otto, a member of the modelling group and a professor of biomathematics at the University of British Columbia, said skepticism of B.C.'s COVID-19 data is warranted, but the current trend in Canada and globally is one of relative stability.

Otto said she's cautiously optimistic that B.C. is headed for a period of ongoing infections due to waning immunity, but will avoid a massive new wave of cases.

WASTEWATER AND VACCINATION UPDATES

Wastewater surveillance in the Lower Mainland can help fill in the gap in information on COVID-19 transmission caused by B.C.'s testing criteria, but the most recent data available on the BCCDC's website is for the week of Oct. 9 through 15. 

As of that date, the BCCDC described viral loads in Metro Vancouver wastewater plants as "relatively stable" over the preceding two months, "with slow increases in SARS-CoV-2 detection at certain plants."

The available wastewater data does not suggest a dramatic drop in transmission was imminent as of Oct. 15.

High levels of immunity from vaccination and previous infection have kept transmission fairly steady in B.C. over the last few months, a dynamic the COVID-19 Modelling Group summarizes as follows in its most recent report:

"In late 2022, most individuals have been exposed to the virus, either by infection, vaccination, or both. With few individuals currently susceptible, new infections substantially reduce the remaining susceptible fraction, causing the growth rate, r, to decline from day to day."

The report warns, however, that waning immunity has allowed the growth rate to increase in European nations and other Canadian provinces, and that B.C. is likely to see the same dynamic.

The province is currently offering residents booster doses of Omicron-targeting bivalent vaccines. During the week that ended Oct. 22, a total of 175,455 new doses were administered, the highest weekly total since the latest booster campaign began.

Roughly 61 per cent of those doses – approximately 107,000 shots – are considered fourth doses, meaning they were administered to people who had already had their original two-dose course of vaccine and an initial booster dose.