Manitoba’s contact-tracing force likely inadequate to stem tide Science inexact, but team of fewer than 300 appears to be fighting a losing battle with rampant COVID community spread
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This article was published 17/11/2020 (864 days ago), so information in it may no longer be current.
The number of foot soldiers working to track down contacts of COVID-19 cases in Manitoba appears to be well short of what will be needed before the province lifts code-red restrictions.
Canada’s chief public health officer Dr. Theresa Tam told the Free Press Tuesday that contact tracing works only when virus spread is “manageable,” and that’s the reason Manitoba and other provincial governments have imposed increasingly stringent public-health orders.
“Restrictive measures were put in place to get the cases under control,” she said. “Honestly, during that time, capacities have to be assured, prepared and built, so that if you were to relax measures, that capacity is there to do the testing, detecting and isolation.”
Manitoba has ramped up its contact-tracing complement with help from the Canadian Red Cross and Statistics Canada. There are currently 293 staff working each day.
Like most other jurisdictions, Manitoba sorts its contact-tracing staff into three jobs: interviewing new COVID-19 cases, notifying their contacts and then following up with both to see if they need help and are following public-health rules.
“A number of jurisdictions are unable to do that rapid contact tracing, given the number of (new) cases per day, and how many contacts they were having. This has begun to be overwhelming the actual public-health systems’ ability to do that,” Tam said.
Coronavirus cases in Manitoba have rocketed skyward over the past two weeks. The five-day test-positivity rate hit an all-time high of 13.6 per cent Tuesday.
“A number of jurisdictions are unable to do that rapid contact tracing, given the number of (new) cases per day, and how many contacts they were having. This has begun to be overwhelming the actual public-health systems’ ability to do that.”
– Canada’s chief public health officer Dr. Theresa Tam
The Free Press surveyed 15 infectious disease experts, most of whom said they believe Manitoba needs more contact tracers.
There are various estimates of the adequate ratio of tracers to cases in order to be effective in reducing community spread of the virus.
Dr. Carl-Étienne Juneau, a public-health researcher at Université de Montréal, has studied the effectiveness of contact tracing. He noted that China put about five tracers on every case, while some American jurisdictions have used as many as 15 per case.
The science is, quite clearly, inexact.
A team at George Washington University in the U.S. capital has created a tool to help countries assess their needs, based on typical ratios for the numbers of contacts and the daily workload for tracers.
When inputting the number of cases over the past 14 days, and the daily average during that period, the GWU tool suggests Manitoba would need between 1,087 and 1,111 staff instead of the existing 293.
Complicating matters is that the data on Manitoba’s online dashboard differs from the numbers in the Health Department’s daily bulletin, changing the GWU tool’s calculations.
“Ideally, we’d want all (contacts) to be reached (within 24 hours) so that those who need to isolate or be tested can do so, but I don’t think this is happening for most units– particularly those that are quite strained.”
– Dr. Robyn Lee, an epidemiologist
The Free Press has asked the provincial government for information on the average number of contacts per case and the average workload for contact tracers, but has, thus far, been unsuccessful in obtaining the data.
Manitoba has reported an average of 366 or 374 new cases per day over the past two weeks (again, based on the daily bulletin or online dashboard).
That would suggest the province needs a minimum of 1,830 tracers.
“This is a rough estimate,” Juneau stressed.
He and five other doctors said Manitoba’s contact tracing will work only if it can spot cases early.
“Ideally, we’d want all (contacts) to be reached (within 24 hours) so that those who need to isolate or be tested can do so, but I don’t think this is happening for most units — particularly those that are quite strained,” wrote Dr. Robyn Lee, an epidemiologist affiliated with the University of Toronto and Harvard University who works in Quebec’s Far North.
“Some exposures may not be as clear-cut as others, so they might take more time to complete. I would think that this, too, might vary by location,” Lee wrote, noting that health-care workers would have scores of contacts.
Some experts also pointed to research about the quality of contact tracing. Trackers placing calls need to come off as non-judgmental while pressing people to reveal whether they had respected public-health guidance.
Dr. Brent Roussin, Manitoba’s chief public health officer, would not say Tuesday whether the province has enough capacity as is, in his view.
He instead said the province is building excess capacity, and is nearing the ability to trace 700 cases a day. It is not clear, however, whether that number represents new positives or all active cases.
“Right now we’re looking to even expand that further, of course,” Roussin told reporters. “We just wanted to make sure we had excess capacity.”
“Right now we’re looking to even expand that further, of course. We just wanted to make sure we had excess capacity.”
– Dr. Brent Roussin on Manitoba’s contact tracing capacity
Yet, Manitobans have reported getting calls from public-health officials more than a week after someone they know has tested positive.
Tam added that it’s entirely up to provinces to figure out what their needs are and ask Ottawa when they lack personnel, suggesting the federal government plays no role in assessing how many tracers are required.
Both she and Roussin stressed that if the public doesn’t limit contacts, cases will remain spreading at levels that can’t be effectively traced.
Ontario cities and some American states have temporarily given up on contact tracing because the number of contacts have outpaced available resources, something Manitoba is trying to avoid.
Roussin has repeatedly cited a recent example of one individual with COVID-19 who had 83 contacts in multiple venues.
He said there have been reports of Manitobans swearing and screaming at public-health nurses doing contact tracing.
With files from Danielle Da Silva, Katie May and Michael Pereira