B.C. wastewater showing increases in COVID-19 concentrations as new variant spreads

The exterior of the B.C. Centre for Disease Control office in Vancouver is seen in this photo from the centre's website. (bccdc.ca)

For the first time in months, weekly wastewater data released by the B.C. Centre for Disease Control shows increasing concentrations of COVID-19 at most monitored treatment plants around the province. 

As of Thursday, only the Lulu Island (Richmond) and Comox Valley wastewater facilities were not seeing at least a slight uptick in coronavirus concentrations.

The other four facilities in Metro Vancouver, as well as plants in Kamloops, Kelowna, Penticton, Victoria and Nanaimo all showed increases.

While the absolute number of copies of the virus found at all treatment plants remains quite low relative to the levels seen throughout the pandemic, the increasing trend – if it continues – suggests next month's counts of infections and hospitalizations will also rise from their current lows.

B.C. has hit new lows for 2023 hospitalizations in each of the last three monthly updates from the BCCDC, with the most recent data showing just 76 test-positive patients in hospital. That's down from a high of 356 at the start of this year and the lowest official hospitalization count the BCCDC has reported in two years. 

The wastewater trend is also notable given the recent emergence of the EG.5 strain of SARS-CoV-2 around the world. 

The World Health Organization added EG.5 – a sublineage of the Omicron variant of the coronavirus – to its list of circulating variants that are under monitoring on July 19. Earlier this week, officials estimated that the strain accounted for one in six cases in the United States and one in seven in the U.K.

Dr. Isaac Bogoch, an infectious disease specialist at University Health Network in Toronto, told CTVNews.ca he expects EG.5 to behave similarly to what was observed with other sublineages of Omicron, with the latest variant gradually becoming the most dominant sublineage around the world.

Bogoch also said he expects EG.5 to affect Canada similarly to other Omicron waves.

“Like we’ve seen in the Omicron era and even before the Omicron era, COVID will disproportionately impact certain cohorts,” he said.

“So sadly, we’re going to see, probably, a corresponding rise in hospitalizations, especially among people who are more susceptible to severe illness — those are older people and people with underlying medical conditions.”

The BCCDC's most recent data on whole genome sequencing shows EG.5.1.1 – one of the EG.5 lineages circulating in Canada – accounted for 8.16 per cent of samples sequenced during the week of June 25 to July 1. It accounted for 13.01 per cent of sequences during the week of July 9 to 15, the most recent week for which reliable data is available on the BCCDC website.  

With files from CTVNews.ca's Noushin Ziafati