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Minnesota has updated its COVID-19 model. Here’s what it tells us

The new model incorporates more recent data on the spread of novel coronavirus in the state.

The latest version of the model projecting COVID-19’s trajectory in the state showing various scenarios.
Minnesota Department of Health

The Minnesota Department of Health on Wednesday unveiled the latest version of a model projecting COVID-19’s trajectory in the state.

The model was built by MDH in conjunction with the University of Minnesota, and the latest version, “3.0,” takes into account new information that wasn’t available the last time the model was publicly released, on April 10.

Here’s what you need to know about Version 3.0.

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What’s different about this model versus the last one? 

In a web tutorial (you can watch it yourself here or see the slides here), State Health Economist Stefan Gildemeister outlined some key changes to the model since it was last publicly unveiled, including but not limited to:

  • Asymptomatic cases: The previous version assumed 25 percent of cases were asymptomatic. The new version assumes 41 percent are asymptomatic.
  • Out-of-hospital deaths: The new model accounts for the fact that some Minnesotans who get very sick are dying outside of hospitals. For example, some older Minnesotans have health care directives asking drastic measures not be taken to keep them alive.
  • Social distancing: The new model downgrades the effectiveness of Minnesota’s mitigation strategy. Previously, it assumed initial physical distancing reduced contacts by 50 percent and the stay-home order reduced contacts by 80 percent. Those numbers have been revised to 38 percent and 55 percent, respectively.
  • New Minnesota data: When the model was last unveiled, Minnesota had seen 57 deaths. In the new version, data has been fitted to actual hospitalizations and deaths reported in Minnesota up to April 25, by which time there had been 797 hospitalizations and 244 deaths in the state.
  • New U.S. data: Other updates include new parameters due to new U.S. data. Previously, much of what was known about the virus came from China, where different demographics and social structure mean different effects.

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In the aggregate, these changes relative to Version 2.0 suggest slightly less time until Minnesota sees infections and ICU needs peak and higher mortality.

What does the model say about when the disease will peak now? And how many deaths are expected?

Gildemeister walked through several scenarios the modeling team put together. Please note that all the below numbers are estimates — not precise predictions.

Minnesota Department of Health
Where are scenarios 2 through 4? They’re outdated now because they were constructed under Version 2.0 assumptions, but you can read about them here).
Scenario 1: The control scenario, never actually plausible because Minnesota began social distancing measures in mid-March.If Minnesota had actually done nothing the model predicts the following (this do-nothing scenario looks different than it did under Version 2.0 because of the new underlying assumptions):

  • ICU peak: May 11
  • Top ICU/ventilator demand: 4,991 beds
  • Mortality by the end of pandemic: 57,035
  • Mortality by the end of May: 42,032

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Scenario 5: The stay-at-home order ends May 18, followed by three weeks of physical distancing similar to what was in effect before stay-at-home, and continued physical distancing for vulnerable people.

  • ICU peak: June 29
  • Top ICU/ventilator demand: 3,397
  • Mortality by the end of pandemic: 29,030
  • Mortality by the end of May: 1,441

Scenario 6: Stay-at-home ends May 31, followed by three weeks of physical distancing similar to what was in effect before stay-at-home, and continued physical distancing for vulnerable people.

  • ICU peak: July 6
  • Top ICU/ventilator demand: 3,006
  • Mortality by the end of pandemic: 28,231
  • Mortality by the end of May: 1,388

Will more testing for COVID-19 have any effect on how bad the disease gets?

Minnesota Department of Health
It may — the model also considers how things could change based on testing.

Gildemeister noted these are hypothetical scenarios, since testing protocols are still being developed, but stressed they are designed to show a range of possible outcomes. The model assumes people who test positive isolate to reduce contact — and transmission — with others.

Scenario 5a: A worst-case testing scenario layered on scenario 5 where the tests are low-sensitivity and fewer people are tested.

  • ICU peak: June 29
  • Top ICU/ventilator demand: 3,150
  • Mortality by the end of pandemic: 26,914
  • Mortality by the end of May: 1,430

Scenario 6b: A best-case testing scenario layered on scenario 6 where tests are highly sensitive and widely available.

  • ICU peak: July 13
  • Top ICU/ventilator demand: 2,444
  • Mortality by the end of pandemic: 22,589
  • Mortality by the end of May: 1,375

Currently, the model does not account for those who came into contact with a positive case also isolating themselves to avoid further spread. The state’s contact tracing program aims to promote that by informing people if they’ve come into contact with someone who’s tested positive for COVID-19.

What would happen if we stayed at home way past the end of May? What if some new treatment becomes available?

Minnesota Department of Health
There are also scenarios addressing these questions, which are bound to be on people’s minds given federal guidelines about reopening the economy and promising news about the antiviral remdesivir’s  effect on COVID-19.

Scenario 7: This scenario looks at how following federal guidelines to, among other things, wait to open up until there’s a 14-day downward trajectory in cases would affect the COVID-19 curve.

Gildemeister said that would likely mean a stay-at-home order into September. Relative to scenario 6 (where the stay-at-home order ends May 31), it has modestly fewer deaths spread out over a longer period of time.

  • ICU peak: July 6
  • Top ICU/ventilator demand: 1,034
  • Mortality by the end of pandemic: 26,294
  • Mortality by the end of May: 1,388

Scenario 8: This looks at following the federal guidelines, plus accounts hypothetically for recent research on remdesivir, which early data suggests can reduce hospital stays and possibly mortality.

  • ICU peak: July 6
  • Top ICU/ventilator demand: 1,034
  • Mortality by the end of pandemic: 25,392
  • Mortality by the end of May: 1,388

So is the model right?

Critics of MDH’s model have often pointed out that the number of deaths it predicts tends to be higher than other models — like one developed at the University of Washington. 

And some say the numbers just aren’t plausible. The scenarios presented estimate there could be between 1,375 and 1,430 deaths by the end of May in Minnesota. So far, Minnesota has seen 638 confirmed COVID-19 deaths, and nine presumed COVID-19 deaths.

To hit the estimated deaths by the end of the month would require, on average, between 41 and 44 deaths per day for the rest of the month. Minnesota has averaged 22 deaths per day in the last week.

“We hope these are pessimistic estimates, but it’s certainly a plausible outcome with the assumption of [continued increased ] spread and wider spread among the population,” Gildemeister said.