Number with COVID-19 in B.C. hospitals rises again as BCCDC tweaks wastewater reporting

A disposable face mask is seen in this file photo from Island Health. (Island Health/Facebook)

The number of people in hospital with COVID-19 in B.C. rose again this week, reaching its highest level since mid-January.

There were 250 test-positive patients in hospitals across the province as of Thursday, still below the 255 that was the lowest total seen in 2022, but well above this year's low of 188.

The number of COVID-19 patients in B.C. hospitals on Thursdays in 2023 is shown. (CTV)The number of COVID-19 patients in B.C. hospitals on Thursdays since the province switched to a "hospital census" model in January 2022 is shown. (CTV)

The hospitalization totals reported by the B.C. Centre for Disease Control every Thursday include both patients who are admitted because of serious cases of COVID-19 and those who are admitted to hospital for other reasons and test positive incidentally.

Health officials estimate that between 40 and 50 per cent of reported hospitalizations are caused by the coronavirus, while the rest are incidental.

Since the BCCDC began including incidental cases in its hospitalization total in January 2022, there have been as many as 985 people in hospital on Thursdays and as few as 188.

CASE DATA

Recent increases in hospitalizations have come alongside increases in other metrics monitored by the BCCDC each week.

On Thursday, the centre reported 405 new, lab-confirmed cases of COVID-19 during the most recent epidemiological week, which ended March 18.

That's an increase of about eight per cent from the 374 reported last week for the period that ended March 11. This week's total is also the highest the BCCDC has reported since Jan. 26, when it announced 408 new cases detected during the week that ended Jan. 21.

Official case counts only tell part of the story, however, as restrictive testing eligibility criteria means only a small fraction of B.C. residents qualify for the kind of test that is included in the BCCDC's weekly updates.

The results of at-home rapid tests are not collected or reported, and experts estimate that the official case count underestimates the number of actual infections in B.C. each week by roughly 100-fold.

WASTEWATER CHANGES

To complement the official case count, the BCCDC also monitors the concentration of SARS-CoV-2 in wastewater at treatment plants around the province.

For the last several weeks, wastewater data has shown increasing concentrations at all monitored plants in B.C.

While that trend has corresponded with rising trends in other metrics, it's difficult to say how significant the surge in wastewater concentrations has been, because the BCCDC recently changed its approach to testing.

"On Feb. 28, 2023, BCCDC began using a more sensitive test for SARS-CoV-2 in wastewater," reads a statement added to the wastewater reporting page on the BCCDC website last week. 

"Increases in the viral signal after this date compared to before it may be due, in part, to this change. Please use caution when comparing data before and after Feb. 28, 2023."