May 05, 2020

SFU professor Caroline Colijn’s research and modelling methods have been helping to inform B.C.’s health policy on COVID-19 since the pandemic’s start. While those efforts continue, new funding will also take her research further to measure how B.C.’s health policy changes are faring.

Colijn and her team are recipients of funding from Genome B.C., a non-profit research organization that leads genomics innovation on Canada’s West Coast, to develop a statistical test to measure the effects of COVID-19 health policy changes.

The funds will also be used to develop models estimating the strength of control measures, projecting the effects of new control measures, and determining the effectiveness of existing measures based on comparisons between locations.

“Right now, there aren’t a lot of simultaneous tools that help us do real-time estimates of how well some measures are working,” says Colijn.

As well, the test could be used beyond short-term forecasting for B.C. and applied to Canadian and international data.

As a Canada 150 Research Chair in Mathematics for Evolution, Infection and Public Health in SFU’s Department of Mathematics, Colijn carries out research that intersects the fields of mathematics, epidemiology and the evolution of pathogens.

Since February, Colijn and her team have been working closely with the B.C. Centre for Disease Control (BCCDC) to develop mathematical models that test the effectiveness of physical distancing measures adopted by the province in the face of the ongoing pandemic.

The effectiveness of physical distancing

Colijn is also an author of a new research paper, Estimating the impact of COVID-19 control measures using a Bayesian model of physical distancing, which estimates the impact distancing measures have had on overall contact rates in the population.

The paper concludes that physical distancing measures have been effective in helping to drive down the number of COVID-19 cases and hospitalizations reported in B.C.

“We looked at reported cases over time, and adjusted for underreporting and changes in testing over time,” says Colijn, adding that her model does not specify which particular measures led to changes in contact patterns in the population, but based on its broad findings, suggests that there may be scope for cautiously relaxing some of these measures going forward.

However, the findings also recommend continuing with intermittent distancing measures to control COVID-19 transmission, and caution against relaxing restrictions significantly as this could risk an exponential surge in the number of infections.

“If we relax it a little bit, keep it within the threshold, then it (number of cases) keeps declining, but at a slower rate.”

Colijn adds that widening testing for COVID-19 would also support relaxing restrictions. But for testing to be used as part of public health strategy, it needs to be coupled with isolating cases, finding more cases to test so as to trace contacts of people who are positive, and active case finding.

“Testing alone doesn’t do the trick, it’s stopping the transmission that is key.”

The road ahead for B.C.

“The picture in B.C. is optimistic as the public has done a great job of following guidelines,” she says. “We have been able to prevent high levels of mortality and infections in the general population, without overrunning our healthcare system and ICU capacities.”

This outcome will facilitate some relaxation in distancing measures and attempts to reopen the economy, which would likely be coupled with strong monitoring, widened testing, contact tracing and isolation of cases, says Colijn.

“And if we see more severe problems, there should be a willingness to go back to what we know works. The last thing we would want is to get complacent and undo the effects of the good that has been do so far.”