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Chat with a U of S Epidemiologist

March 27, 2020

Those who have been following our COVID-19 Crusade to have better data available for Saskatchewan residents know we’ve been looking for ways to predict spread instead of report after the fact. We called that a search for a leading indicator instead of a lagging indicator. At the risk of repetition, the idea is akin to tracking calories and exercise to see if we will be gaining weight instead of stepping on the scale after the fact to see if we gained weight. If we know we’ve consumed more calories and can correct immediately with some jumping jacks, we can prevent the weight from being gained in the first place. And anyone that’s ever started an exercise regimen will know that weight takes some time to start dropping. Similarly, this coronavirus takes some time to display symptoms and social distancing takes some time to start to show results.

Yesterday afternoon, I received a call from Dr. Nazeem Muhajarine, a professor of Epidemiology at the University of Saskatchewan. I was initially worried that I had gotten something horribly wrong but he actually called to thank me for my work and offer his assistance! We had a great discussion about where we’re at in Saskatchewan.

Leading Indicator

The best part of our conversation was that, from a graphing standpoint, Dr. Muhajarine had some insights into leading indicators that will be familiar to anyone with clinical testing background. I’d already pondered looking at the number of tests and percentage of positive tests as a potential indicator that there is a growing population of untested positives in the community. But I’d left it alone because I’d convinced myself there were too many unknowns. Doctor Muhajarine informed me:

“In clinical trials, they look at how many patients it takes for a successful treatment outcome. This is similar to evaluating the number of tests it takes to yield a case. There are two possible causes that increases the yield; one is that there are more cases available from the population. The second is that we are doing a better job in case finding – that is, targeting potential positives. We already know that the criteria for getting tested has not changed, that is, we are targeting our tests. But we need to do more testing to find the cases that are not in the targeted groups. There are many more cases out there without showing symptoms.”

You had me at “clinical trials,” Doctor. So starting today (and thanks to a timely release of tests per day from the SHA) we will have a new graph starring at the top of our blog: percentage of positive tests. I had already been casually tracking it and can tell you that it has more than doubled in the last week or so. A good indicator that we’re still spreading the virus and that more tests will continue coming back positive.

A Small Diatribe (Rant)

I have also made the case that we simply need to be doing more testing. Some have argued that with so many negative test results, we’re probably doing too much testing. Our own Chief Medical Health Officer, Dr. Saqib Shahab has argued against broader testing, but finally relented to expand testing beyond those that have recently traveled. As is becoming the norm in this crisis, our provincial government takes a “wait and see, we’re doing enough” stance, argues against doing more, and then, too late, relents.

Dr. Shahab makes comments like “I wouldn’t go into an elevator with 5 people” but then the province gets into a pissing match with Regina for trying to set that as a group limit in that city. I sympathize with the argument for clarity, but it would be wiser to have the province set a minimum threshold and allow municipalities to set the rules to match or be more strict (but not less). Is it not possible that there may be cause for different rules in Yorkton than North Battleford or Regina? Maybe the residents in one city are very compliant and in another disobedient? If the province was proving its competence, I guess I’d have less to complain about.

But I digress. I am furious that we weren’t on top of ordering PPE and ventilators back in January. I am just an average idiot citizen. But I still went to Costco mid February to make sure we would have essentials if the virus came to our door. Yes, including one of those Costco packs of TP. Yet our health experts waited until the virus was here to order “a few more” ventilators and didn’t order some extra damned masks? What’s the worst that could happen? They’d order too many and … what? Were they going to go bad sitting on the shelf?!? OK, I’m going to change the title to this section!

I will say, I can empathize with the province trying to balance the economic reality with the health outcomes. But I have no excuse for the SHA leadership, if it is indeed their decision. With politics involved, who really knows?

Sigh. Back on topic…

Testing and A Different Kind of Cluster

Dr. Muhajarine (the epidemiologist) agrees that we need to be doing more testing and smarter testing. “If social distancing isn’t complemented by testing, we won’t get ahead of this.” I sense a bit of frustration from him as well. “Dr. Shahab talks about only testing people at high risk of having the virus,” he says, referring to returning travelers with symptoms, “but asymptomatic cases are the highest risk of community transmission.”

So do we test everyone? There are limited tests, and from some reports, even more limited people to conduct those tests. “In Italy, when two or more cases are in a cluster,” such as on a flight, in the same building, event, etc, “they do contact tracing and target that cluster. Test and isolate. Social distancing is a blunt instrument.” Authorities may be on the right track with news that all 110 attendees of a Christopher Lake snowmobile rally dinner are required isolate.

He has other ideas for cluster targeting. Geography, for example. Yesterday I showed an example of the detail in Alberta’s data. They have an interactive map where you can see what areas of Calgary are hit hardest. That sort of data could help inform decisions on where to direct testing resources. Sharpen the testing to more at risk people including health-care workers, elderly, or by age. “At risk” should include people likely to spread as well as likely to have negative health outcomes. Publicize if someone that tested positive was at Costco on Wednesday afternoon, isolate, and test them. Let the asymptomatic carriers be caught within a cluster instead of waiting for symptoms. Symptoms can take a week to appear if they appear at all, and each of those people can potentially spread the virus.

We can’t do this as individuals or as a province if this data isn’t being found. The province will need to make an attempt at cooperating with other levels of government for a change.

At the end of our conversation, Dr. Muhajarine and I agree on two final thoughts. We can do better. We have to.

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