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March 3 forecast reveals continued sharp descent of COVID-19 hospitalizations in Oregon

Two years after initial forecast, OHSU data analyst gratified by Oregonians’ response to public health measures driven by science
OHSU hospital is light up during a wet, dark night. A person is at a bus stop, and about to get on a TriMet bus heading toward downtown Portland.
A person waiting outside Oregon Health and Science University Hospital catches a TriMet bus heading down Marquam Hill on a wet evening in Portland. (OHSU/Christine Torres Hicks)

The number of people hospitalized with COVID-19 in Oregon will continue its sharp descent as the coronavirus finds an ever-dwindling pool of susceptible people, according to the latest forecast from Oregon Health & Science University.

A total of 404 people remained hospitalized with COVID-19 in Oregon as of Thursday, March 3, according to the latest figures from the Oregon Health Authority. That’s well ahead of previous projections and likely reflects the fact that the highly contagious omicron variant is finding fewer people who remain susceptible to severe illness.

The new forecast projects hospitalizations will fall to 300 by March 18.

Peter Graven, Ph.D. (OHSU) A person with light hair smiling.
Peter Graven, Ph.D. (OHSU)

“There aren’t enough susceptible people in Oregon right now to generate another surge in hospitalizations,” said Peter Graven, Ph.D., director of the OHSU Office of Advanced Analytics. 

Graven expects hospitalizations to continue falling as the omicron variant finds fewer and fewer people who haven’t already been infected, vaccinated or both. Recent laboratory findings from OHSU found that the combination of vaccination and infection generates a form of “super immunity” against subsequent exposures to the SARS-CoV-2 virus.

The new OHSU forecast estimates about 13% of Oregonians are still susceptible, either because they haven’t been recently infected or vaccinated, or because their previous immunity has waned. But Graven said that’s not enough to generate another big surge in illness severe enough to land someone in a hospital bed.

At least until another variant emerges that breaks through existing immunity, Graven said he doesn’t currently foresee another wave of severe illness on the horizon.

Graven said the faster-than-expected drop in hospitalizations and reported infections over the past month likely suggests that a sizable proportion of Oregon’s population has already been exposed to the virus. The precipitous decline in cases and hospitalizations means the virus is running out of susceptible hosts, he said.

Graven estimates roughly two-thirds of Oregon’s population has been infected at some point, including those who had a breakthrough infection after vaccination.

“We’ve created a large buffer of people who have already had it,” he said.

On Jan. 27, a total of 1,130 people were hospitalized with COVID-19 in Oregon in what turned out to be the peak of hospitalizations during the omicron surge. The omicron variant was first confirmed in Oregon on Dec. 14 and quickly gained traction, driving a wave of hospitalizations after Dec. 21, when a low of 338 people were hospitalized statewide from the previous wave driven by the virulent delta variant.

Sounding the alarm with data

Today’s forecast comes a little more than two years to the day after the first confirmed infection in Oregon on Feb. 28, 2020, when Graven began forecasting the trajectory of the expected impact of the pandemic on the OHSU Health system.

Those initial forecasts crystallized the impact in a way nothing else had.

Renee Edwards, M.D., M.B.A (OHSU) A person with light hair, smiling.
Renee Edwards, M.D., M.B.A (OHSU)

“It scared me to death,” Renee Edwards, M.D., M.B.A., senior vice president and chief medical officer for OHSU Health, said then. “We were already preparing for the pandemic, but we were talking in generalities. Peter’s model made COVID-19 an absolute stark reality. It gave us a timeframe and brought everything into focus.”

For his part, Graven has been gratified by Oregonians who responded to the projections by taking public-health measures seriously and keeping hospitalizations relatively low in Oregon compared with other states.

However, he’s also acutely aware of the costs.

“Those lines going up and down on the charts represent people in the hospital and lives lost,” he said. “I do have a sense of pride in how Oregonians managed through this pandemic, while recognizing the economic and personal sacrifices we’ve all had to make to save lives.”  

The omicron peak fell just behind the pandemic high of 1,178 people hospitalized during the peak of the delta-driven wave on Sept. 1, 2021.

Oregon, Washington and California jointly announced this week that all three states will lift indoor mask requirements on March 11. Oregon Gov. Kate Brown announced the statewide public health state of emergency will end on April 1.

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