Oregon could reach COVID-19 herd immunity in December, OHSU reports

Authors: Ashley Korslien, Anthony Macuk (KGW)

PORTLAND, Ore. (KGW) — Oregon could be on track to reach herd immunity against the delta variant of the novel coronavirus by the end of the year, according to a data scientist at Oregon Health and Science University.

Dr. Peter Graven has been tracking the virus since the start of the COVID-19 pandemic, and his latest modeling shows Oregon could hit the herd immunity threshold as soon as Dec. 26.

Herd immunity refers to the point at which a virus can no longer easily circulate because a large percentage of the population has been vaccinated or achieved natural immunity through a prior infection.

The minimum required percentage varies depending on the virus. The delta variant is more transmissible than the original version of the novel coronavirus and has an estimated threshold of 85%, according to Graven.

The delta variant reached the United States earlier this year and became the dominant strain of the virus in circulation, contributing to a renewed surge in cases and a record-high number of COVID patients in Oregon hospital beds in early September.

COVID cases in Oregon have trended downward since then, but the state’s hospital beds remain relatively full, matching the height of previous case waves.

“Our most recent statewide hospital number was 585 that I reported, that’s still the peak of the fall and winter surge of last year,” Graven said. Statewide, 24% of Intensive Care Unit beds were occupied by COVID patients as of Oct. 12, according to OHSU.

Cases should continue to fall in the coming weeks, and projections show the number of hospitalized COVID-19 patients statewide should drop to about 241 by the end of the year, he said, easing the strain on hospitals.

Roughly 71% of adults in Oregon have received at least one dose of a vaccine, according to OHSU, and Graven estimates 34% of Oregonians have been infected with COVID-19 at some point during the pandemic.

However, more than one fifth of Oregonians are still vulnerable to infection, he said, and he projects the state will face another 177,000 infections before reaching herd immunity in late December —  plus hundreds of additional deaths.

“I would estimate probably about 700 deaths in fact,” he said. “That to me is not really a relief. That’s going to be more people who are going to have to go through this.”

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