Since the dawn of the COVID-19 outbreak, UBC clinical professor Dr. Danuta Skowronski (DS), and UBC professor Dr. David Patrick (DP), both epidemiology leads at the BC Centre for Disease Control, have been tracking and forecasting the spread of the virus—offering insight that has proven instrumental in informing B.C.’s emergency health response.
They share why surveillance and modelling are key and reveal what we can expect as the virus continues to evolve.
When COVID-19 first came onto the scene, what was your initial reaction?
DS: On the morning of December 31, 2019, I began my day like any other—scanning online bulletins for news of emerging pathogens. That morning, reports of a virus cluster in China caught my attention immediately and within a few hours, I had drafted a bulletin alerting clinicians and public health officials across B.C. Even from the early days, I sensed this new threat was to be taken seriously.
DP: For me, the watershed moment was when we began to see cases in regions adjacent to Wuhan, China. The whole reason we care about emerging infectious diseases is exactly this kind of scenario, where we have a virus that spreads easily between humans and there are significant consequences of infection, with no treatment and no vaccine.
What is the difference between surveillance and modelling, and why are they important?
DP: Surveillance comes down to observations we are seeing in real time, whereas modelling is a tool to help project how the pandemic might unfold under various circumstances.
Surveillance and modelling are critical for monitoring how an outbreak is growing, shrinking, or holding steady and ultimately informing the health emergency response in B.C. How many ventilators are needed? How many critical care beds need to be reserved? How will returning to work and school impact the transmission rate? Can apps help with contract tracing? These are some of the questions our work has and continues to help inform and answer.
“If we let down our guard, if we relax physical distancing too much, more cases are inevitable. We need to strike the right balance between health-care impacts and socio-economic consequences.”
Dr. Danuta Skowronski
What did your first model look like? How does it compare with the current model?
DS: In the early days, our challenge was to understand the potential scale of the threat we faced. To inform that, in early February I provided some very basic spreadsheet calculations using severity information emerging from China.
With those back-of-the-envelope calculations we were able to show that comparing the potential number of hospitalizations, ICU admissions or deaths to a nasty “flu season” could be a serious under-estimation. Instead, if unchecked, the order of magnitude might be more akin to the worst influenza pandemic on record—the 1918 Spanish flu pandemic.
We needed emergency planners and the health care system to prepare for something beyond recent experience. Those early, but startling statistics got their attention.
“Surveillance and modelling are critical for determining whether an outbreak is growing, shrinking, or holding steady and ultimately informing the health emergency response in B.C.”
Dr. David Patrick
DP: As we accrued cases, we were able to inform our models based on B.C. data. We soon began building on our observations, developing sophisticated models to predict the spread with more precision, looking at the nuanced interactions between individuals by age and by geographical setting. Those more precise models have proven critical for developing forecasts for various situations, like returning to work and re‑opening schools.
What if the virus has evolved by the time a vaccine is ready? What happens then?
DP: This virus will evolve. All viruses evolve. But unlike influenza that can exchange genetic material rapidly between pigs and birds and humans and come up with something brand new, this novel coronavirus is not mutating at a rate where we anticipate a new vaccine could not be utilized.
We are going to be watching what this virus does very carefully over time, and the equitable distribution of the vaccine is one of the areas we are now modelling to help inform the Office of the Provincial Health Officer.
Based on your work, how far away are we from herd immunity?
DS: This virus is humanized now, it’s not going away—we have to find a way to live with it. In B.C., like elsewhere, our population immunity is not much better than it was when COVID-19 first arose. If we let down our guard, if we relax physical distancing too much, more cases are inevitable. We need to strike the right balance between health-care impacts and socio-economic consequences.
The role of seasonality remains uncertain but, in the absence of herd immunity, we should be preparing for a series of undulations in the epidemic curve as we relax or enhance mitigation measures.
DP: We have not had enough exposure in the population to achieve herd immunity yet. Without any additional tools (new therapeutics or a vaccine) to manage the spread, the next several months will be a test of our society and our will.
Maintaining physical distancing, washing our hands, staying at home when we’re sick and taking other preventative measures will remain critical.