What’s in a model?

Turns out South Dakota health officials are reluctant to share that information.

The people behind the state’s coronavirus response model, which Gov. Kristi Noem unveiled one week ago, have failed to release data used to make their assumptions. Meanwhile, health officials from the state’s three large health Systems – Avera, Sanford and Monument Health – won’t elaborate on how they contributed to the process.

“Sanford Health contributed to the state’s model,” spokesman Shawn Neisteadt said. “The state could share how many models it used for its prediction.”

Neisteadt declined to elaborate on what Sanford contributed.

Avera spokesman Jay Gravholt acknowledged that the health systems worked with the state, but he deferred questions to the state. Monument Health in Rapid City did not respond.

More:Projections: Up to 600,000 South Dakotans could get coronavirus, will peak in mid-June

The governor unveiled the model at her daily coronavirus press conference on April 3. It shows that cases of COVID-19 will peak in South Dakota by mid-June. Even before that presentation, the Argus Leader had asked the state to provide data it was using for any modeling.

This week, the state emailed an equation it says it used to calculate the model, but the data used in the equation was not included.

The model, which has produced the now ubiquitous curve graphs that have dominated policy debates since the onset of the coronavirus pandemic, is known as SIR model. Epidemiologists have been using them for nearly a century to predict outcomes in an outbreak of contagious disease. They measure the number of susceptible people to a given population and infectious disease, and predict infection and recovery rates given various data points and assumptions.

The models, experts say, are not fixed in time, and as Dr. Allison Suttle, Sanford’s chief medical officer, said during the April 3 press conference, their assumptions change as the behaviors of people in the infection area change.

“It is just a model, and it will change, and it depends on all of our behaviors and the virus itself and the biology of the virus, which we have to respect,” Suttle said.

In the April 3 release of the South Dakota chart, Noem was joined by state epidemiologist Josh Clayton, as well as Suttle and doctors from Avera and Monument Health. At its peak in mid-June, the curve predicted South Dakota will need 5,000 hospital beds and 1,300 ventilators, capacity the health system is attempting to build.

The governor was blunt: Some victims of COVID-19 would not recover.

The graph was different than other independent models that show South Dakota caseloads peaking in April, including the model published by the University of Washington’s Institute of Health Metrics and Evaluation, which as of April 10, calculated a peak on April 29.

Clayton addressed the other models, saying they didn’t have South Dakota specific data. The graph released April 3 was based on information as recent as April 2, and Clayton also said that it would change.

Of the three doctors, Dr. Brad Archer, the chief medical officer for Monument Health, was the most detailed in explaining how his health system assisted in developing the model.

“We at Monument Health endorse this model, and we appreciate the opportunity to have our predictive analytics team engage with each of you as we came to this conclusion,” Archer said.

Dr. David Basel, Avera’s chief medical officer, said his health system “fully supports” the model.

Suttle said: “It has been a collaborative effort, and it has been wonderful to see all the systems come together with the state to come up with one story – one story we can tell South Dakota.”

One week later, on April 10, Minnesota released its revised model. It included more than three dozen pages of supporting materials, include several different scenarios using different formulas, assumptions, data and technical documentation.

“After designing and building our model, we are sharing details about our modeling to better inform the public of what information contributes to decision-making, and to explain why guidance like social distancing is critical to protect the health of Minnesotans,” the state’s COVID-19 web pages says.

“Basically,” Minnesota Department of Health spokesman Scott Smith said in an email to the Argus Leader, “we wanted to be as transparent as possible.”