New Brunswick's mid-December COVID modelling did not account for Omicron variant

Soaring COVID-19 case numbers have already blown past modelling numbers released by the New Brunswick government just two weeks ago — numbers, it turns out, that did not take into account the fast-spreading Omicron variant.

University of New Brunswick physicist Dr. Sanjeev Seahra says he provided the modelling on Dec. 19 and at the time, there was still not enough data to incorporate Omicron into the projection.

Even so, Chief Medical Officer of Health Dr. Jennifer Russell said two days later that the numbers did reflect Omicron's growth.

"As you can see from this slide, when Omicron replaces Delta as the dominant strain in this province, as is happening elsewhere, we expect the number of COVID-19 infections will double every three days," Russell said Dec. 21.

She displayed Seahra's graph, which projected a sharp spike in cases heading into 2022.

"At that pace, our modelling suggests that we could see up to 250 new cases each day by early January and as many as 400 new cases a day by the end of next month," Russell said.

In fact, New Brunswick surpassed the 250-case mark within two days, on Dec. 23 and it surpassed 400 cases on Dec. 29, more than a month earlier than Russell's projection. As of Monday, the seven-day average for daily cases was 656.

Seahra, the chair of UNB's department of mathematics and statistics, says that at the time he did the modelling, Omicron's properties weren't well-known enough to be included.

"On that particular date, Omicron was a very new variant," he told CBC News. "We didn't know the properties back then and we still only have very rough estimates of the properties right now. It is new and emerging science.

"It's possible to construct models with the new variants but to have full confidence in the projections you need more data. You need longer data." 

He said he watched the Dec. 21 briefing in which Russell said the graph depicted Omicron replacing Delta and driving "exponential growth" in cases.

"I guess I was watching it knowing where that graph was coming from, so I didn't find it confusing myself, but maybe I'm not the right one to judge." 

At that briefing, Russell used the graph to explain how dire a threat Omicron posed to the province.

Referring to early indications that the variant produces milder illness in general, Russell said "the jury is still out on that" and said rapid, exponential growth would still lead to more severely sick patients straining the health-care system.