PORTLAND, Ore. — A new viral modeling report suggests that coronavirus is spreading more rapidly in Oregon, according to a statement released by the Oregon Health Authority on Friday.
"We know that COVID-19 is in our communities," said Dean Sidelinger, MD, Oregon state health officer. "This latest model provides us with a sobering reminder that we all need to guard against continued spread, especially as we continue to reopen and the weather gets warmer."
According to the report, transmission rates increased 15 percent after May 15, and 10 percent more after May 22, based on hospitalization data in the state.
The state has seen some of its highest single-day spikes in COVID-19 cases over the past several weeks. Though at least some of the sustained increase in cases can be attributed to an expansion in testing and contact tracing, OHA officials have warned for weeks that the rate of transmission has risen as well.
OHA says that the latest model from the Institute for Disease Modeling is based on data gathered through June 18. It displays three projections — optimistic, moderate, and pessimistic models — that predict how case levels could proceed in the coming days. One scenario predicts that daily cases could rise as much as 20 percent.
"The modeling assumes that hospitalizations from COVID-19 remain stable and testing remains at its present level of approximately 4,000 a day," OHA said.
The optimistic scenario assumes that previous case increases are entirely due to higher testing, and predicts that case counts could remain stable at roughly 180 per day over the next month. OHA said that this is the "least likely" scenario, because it assumes that all new cases will be diagnosed. At present, only about one-third of new infections are traced to a known source.
The moderate model takes into account both increased transmission and expanded testing — predicting that daily infections could rise over the next month to more than 900 per day, with daily hospitalizations rising from eight to 27.
In the worst-case, "pessimistic" model, the rise in cases has been entirely due to increased transmission and not expanded testing. With these conditions, OHA said that infections could rise to more than 4,800 daily, with as many as 82 hospitalizations each day.
"Think hard about your choice of activities, especially as we get close to the Fourth of July holiday," Dr. Sidelinger said. "Ask yourself: how can I reduce my risk and the risk I might pose to people around me?"
OHA asked people to do what they can to suppress the virus: Staying six feet away from other people, wearing a mask, and avoiding large gatherings.
"If you are in a group setting — like a holiday barbecue — stay outside, keep your distance and use a face covering when you’re not eating. Wash your hands frequently and stay home if you’re sick," the agency said.