Health department: More than 34,000 in Sioux Falls have likely had COVID-19

Tens of thousands of people in Sioux Falls and the surrounding area likely had coronavirus and didn't know it or never got tested.

That's one of the takeaways from updated virus modeling and projections released this week by the Sioux Falls Health Department that showed 225,000 people in Lincoln and Minnehaha Counties who remain susceptible to COVID-19, down more than 34,000 from modeling done in late April.

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That means beyond the 1,404 new confirmed cases of coronavirus in the two counties since the old modeling was done on April 29, thousands more likely have or have been infected but didn't get tested because they were asymptomatic or symptoms weren't severe.

"Based on the number of positive cases you know are out there, there's sort of a standard rule that there is probably 10 times that in your community," Sioux Falls Health Director Jill Franken said.

Although the antibodies that recovered coronavirus patients carry are still being studied by scientists and health experts across the globe, Sioux Falls' modeling is based on the belief that people who've healed from COVID-19 infections have some level of immunity for a time.

That's why the number who remain susceptible to the virus in the counties continues to drop as models get updated.

"Everybody who's gotten infected before hand we're taking out of the model because they're not going to get reinfected from this model's standpoint," said Albert Schmidt, a city planner who's been assisting the city's emergency operations center with data analysis.

Other adjustments to the modeling show the average hospital stay for a coronavirus patient is six days, down from 13 days in late April. And the amount of time it takes to see total cases double is 16 days whereas cases were doubling every six days in late April.