Marion County reported 51 new residents with COVID-19 on June 22, setting a new county record. (Screenshot from Marion County Health & Human Services data dashboard)

Marion County on Monday reported 51 residents newly-diagnosed with COVID-19, the highest one-day total since the first local case on March 9.

The number reflects both widespread testing - 540 people got COVID-19 tests back on Monday, also a record - and a higher percentage of those tests coming back positive, at 9.4%.

The percentage of tests that are positive is an important health metric, and one state officials are looking to as Oregon counties reopen and testing ramps up. More people being tested means more cases will be reported. But if the percentage of tests coming back positive grows, it suggests health workers may be missing less serious cases of the virus because the people getting tested are more likely to be sick.

Since the testing began here in March, Marion County has averaged 8% positive tests, with that number falling in recent weeks. The state average is 3% positive tests.

The number of Marion County residents hospitalized is also climbing, an indicator of more serious cases of illness. Salem Hospital reported 21 patients in-house with COVID-19 on June 19, with six more patients who had COVID symptoms awaiting test results. That's the highest number of confirmed patients since mid-April.

Whether the new cases are tied to any outbreaks, new or ongoing, isn't clear - Oregon Health Authority did not respond to questions Salem Reporter sent early Monday afternoon, and Marion County Health & Human Services spokeswoman Jenna Wyatt said epidemiologists are still working to trace recent cases. 

She declined to say if the new cases were related to any ongoing outbreaks, saying that data would be included in the state’s weekly report. Those reports, released on Wednesdays, only include data through the previous Sunday.

Marion County has had 1,352 residents diagnosed with COVID-19 since the beginning of the pandemic in early March. Thirty-five county residents have died. The latest death was reported Monday, a 90-year-old woman who tested positive for the virus on June 18.

The county’s data shows more than one-third of residents diagnosed with COVID-19 in the past three days live in ZIP code 97306, which covers south Salem and Sunnyside. Thirty-two people there were added to the county’s case count since Friday.

Until recent weeks, that ZIP code had one of the lowest rates of COVID-19 in the county. But two nursing homes in the area have active outbreaks. 

Marion County Commissioner Kevin Cameron said county health workers told him new cases over the weekend were connected to testing in a long-term care facility and at the NORPAC plant in Salem, which also has an active outbreak. He said he wasn't told which care facility.

Oregon Health Authority publishes updated numbers for nursing homes once per week on Wednesdays. As of June 14, Boone Ridge Senior Living had reported three residents or employees sick with COVID-19, and Brookstone Alzheimer's Care Center had reported eight cases and one death. Both are in ZIP code 97306.

In other local nursing homes, widespread testing in nursing homes has caused the number of reported cases to climb rapidly in a short period. Elisa Williams, spokeswoman with the Department of Human Services’ aging and long-term care division, said local health authorities are still responsible for testing inside facilities. Wyatt did not immediately respond to a follow-up email asking if Marion County had recently tested in those facilities.

Marion County is one of several Oregon counties that have set new records for cases of COVID-19 in recent days.

Multnomah County, the last county in the state approved for phase 1 reopening, reported 84 new residents with the virus Sunday June 21, Willamette Week reported. That broke the county’s previous record of 49 cases, set on Friday, June 19. Umatilla County also saw a record number of new cases in a single day.

This article was updated to include more information from Kevin Cameron.

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Contact reporter Rachel Alexander: [email protected] or 503-575-1241.