How virus got here, how it spread, and where it remains

Province releases information showing where virus came from and where it remains

For the first time since the COVID-19 pandemic began in B.C., provincial health officer Dr. Bonnie Henry provided significant and surprising details Thursday on where the virus originated, how it spread and where it remains.

Her briefing on the sources for the outbreak was especially revealing. It was on genetic analysis of more than 700 samples of the virus assembled from actual cases in B.C.

Turns out that as the novel coronavirus replicates, it alters just enough to create identifiably different strains, each associated with the most recent place of origin.

B.C.’s initial cases, starting in January, can readily be traced back to China, where the outbreak began. A second group of cases starting in February is associated with the outbreak in Iran.

Indeed, as Dr. Henry noted Thursday, her team made that link regarding a COVID-19 case here in B.C. before the Iranian government admitted to the world it had an outbreak.

But the analysis indicated that many more of the cases in B.C. have been traced to strains of the virus arriving in B.C. from Europe, Eastern Canada, Washington state and other points in the United States.

Those strains of the virus came by plane, by land travel, and via British Columbians returning from other provinces or from overseas or the U.S., where they worked or were on vacation.

Henry also flagged the significance of an international dentistry conference held in Vancouver in early March. It singlehandedly seeded 87 cases in the early days of the outbreak.

“I cannot say it was the only thing that caused our pandemic, by any means,” Henry told reporters. “It was certainly a sentinel event, in the timing of it, along with everything else.”

The data also provided a story about the role that each version of the virus played over time.

The Chinese and Iranian strains were capped off early, contributing few additional cases beyond February and March.

Henry attributed this to the forthright responses of the affected communities in co-operating with public health authorities and in adopting physical distancing and other safeguards.

Too bad that analysis was not available earlier. I’ve lost track of how many emails I received back in March and April, alleging that the government was “covering up” all the cases in Richmond and North Vancouver, code for Chinese and Iranian respectively.

While cases associated with those strains were flatlining, those linked to the Washington-like and European/Eastern Canadian strains continued to climb.

As of May 29, they accounted for the vast majority of the cases in the analysis.

Those strains were harder to contain, being broadly based and in many more communities around the province.

The analysis also backs up something Health Minister Adrian Dix has indicated more than once, namely that the majority of cases in the Vancouver Coastal health region are associated with the Washington state-like version of the virus.

Dix seized the opening during the briefing to reiterate his view that “measures at the border continue to be key for us as we avoid further transmission of COVID-19 in B.C.”

Washington, which has about 40 per cent more people than B.C., reported another 245 COVID-19 cases Thursday, while B.C. logged just five.

Henry said the data cannot be extrapolated to determine precisely how many of B.C.’s cases can be attributed to each of the strains. The genetic analysis was applied to only about one-third of all the cases in B.C. and the sample was not random.

Another set of charts in her presentation told the story of how B.C. has managed to rein in the outbreak, reducing the number of active cases down to just 201.

The decline has been widely reported, but she added some geographical detail that has not been shared with the public before this week.

For the first time, the number of cases was broken down by 12½ health-care delivery areas within the five larger health regions.

One chart showed that since COVID-19 was initially reported in late January, every area has had some cases and the heaviest incidence was in a handful of areas in and around Metro Vancouver.

The more dramatic chart was the one displaying the distribution of cases for the last two weeks of May. Most areas reported only a few cases, and some, including all three in the Vancouver Island Health Region, had none.

Richmond also recorded no active new cases in the past two weeks. (So much for that coverup.)

On closer examination of the geographical data, the outbreak was largely confined to two of the three areas in the Fraser Health region — those comprising Delta, Surrey and Langley, out to Abbotsford and Chilliwack.

Together they accounted for 103 of 144 new cases, or just over 70 per cent. The count included the outbreak at the Langley Lodge long-term care facility (where 23 residents have died from the disease), and a cluster of cases that began with a social gathering where one of those attending had undetected symptoms.

The lingering outbreak in Fraser Health mainly served to underscore a familiar message from Henry: “The virus is still out there in the community, and once you have been exposed to it we have no way of preventing you from getting sick.”

So, yes, B.C has made progress, but she’s not letting us drop our guard just yet.