COVID-19 cases essentially disappearing over the summer followed by an even bigger wave of infection in the fall and winter is what University of Minnesota infectious disease expert Dr. Michael Osterholm has long considered the "worst-case scenario," but Osterholm is gaining confidence that such a scenario won't unfold over the course of the pandemic.
Speaking this week on the Osterholm Update, a COVID-19-focused podcast from the Center for Infectious Disease Research and Policy (CIDRAP), Osterholm said recent trends in America suggest that the virus evolution will likely be a slow burn with peaks and valleys.
"It's a situation where over the course of the last three weeks we've seen the epidemiology of this disease, particularly in the U.S. but also in other parts of the world, giving us enough information to get a sense of what this scenario is likely to be over the course of the next few months," Osterholm explained.
In April, Osterholm led a CIDRAP team that predicted three potential scenarios for the future of the pandemic, which at the time featured Scenario 2 – the "Fall Peak," as seen in the graphic below – featured as the best comparative model for the novel coronavirus. But time has passed, the disease has been studied and a blend of scenarios 1 and 3 is now more likely, per Osterholm.
"What we're seeing right now, in the U.S. in particular, but in other parts of the world, is a hot, burning forest fire of cases," he said. "I feel like the whole human race is the wood that this fire is trying to find and burn. We're not seeing any evidence of slowing down right now.
"What we are seeing is a combination of the two other scenarios that we laid out, one of a slow burn and then one where the hills and valleys, a kind of dimpled landscape, where some areas are impacted for a period of time and then other areas are not, but then more or less switch off as time goes on."
Osterholm says there are 26 states currently experiencing rising case levels, nine states that have leveled off and 15 others (including Washington, D.C.) that are seeing decreasing numbers.
Minnesota has seen a mixture of leveling off and decreasing numbers since the calendar flipped to June, with this week featuring four consecutive days of single-digit deaths.
Why is that?
"I don't know," said Osterholm. "I think that anybody who tells you they know, I would be very cautious about taking much more advice from them. It's possible that over the next couple of weeks, we'll see these 25 states experience the same thing that the other 26 states are, and there will be an increase in cases, but we don't know that."
Here's how each of the three scenarios was described in the original CIDRAP release.
Scenario 1: Peaks and valleys
First wave in spring 2020 followed by a series of smaller waves that last through the summer and consistently over the next year or two, gradually diminishing in 2021.
This scenario could feature outbreaks that vary by location and would depend on what types of mitigation are enforced.
Scenario 2: Fall peak (the one Osterholm doesn't expect)
After the spring 2020 peak, a larger wave arrives in the fall or winter of 2020 with one or more additional waves in 2021. The research says this scenario would be similar to what happened with the 1918-19 Spanish Flu.
Influenza pandemics in 1957-58 and 2009-10 followed a similar pattern.
Scenario 3: Slow burn
Cases and deaths continue to occur but it would likely not require continued mitigation but could result in hot spots of outbreak in certain locations. Past influenza pandemics didn't follow this pattern, but the research says this could happen with COVID-19.
"I now believe that we're just going to see this thing keep burning," Osterholm concluded.