All gatherings of more than 250 people in Oregon will be canceled for the next four weeks in an effort to slow the spread of coronavirus, Gov. Kate Brown announced Wednesday night.

That means many sports and entertainment events, 10K runs, conferences, lectures, religious gatherings of more than 250 people and other planned events won’t happen.

Brown said public schools should remain open. But she said all non-essential school-associated gatherings and group activities — such as parent group meetings, field trips and competitions -- should be cancelled.

The guidance for schools came hours after Oregon’s largest public universities announced a series of policies to keep students safe. University of Oregon, Oregon State University and Portland State University all aim to limit student interaction, including canceling in-person final exams and providing online classes.

Brown also issued guidance for employers, saying that all measures should be taken to “increase physical space” between employees and to limit meetings and stagger work schedules.

“Nobody is immune to this virus. It can touch everyone," Brown said in a statement. “We can’t let fear and anxiety stigmatize people. We are seeing cases across multiple counties and age groups and in people exposed through different circumstances. It’s time for us all to do what we can to slow its spread and take care of one another."

Her statewide ban on large gatherings mimics one that Washington Gov. Jay Inslee imposed on three Seattle-area counties earlier Wednesday, as his state copes with confirmed coronavirus cases approaching 400 with 29 deaths.

Hours before she made the announcement, The Oregonian/OregonLive reported a ban of that magnitude was under consideration and explained what it could spell: a fanless future for any large sports event or concert. It also could cost jobs at Providence Park, other major athletic and entertainment venues, conference facilities and hotels that cater to them.

Its expected impact on Trail Blazers’ games, some of the largest routine gatherings in Oregon, was made moot earlier Wednesday when the league announced it is suspending the season in the wake of a player’s positive test for COVID-19.

So far, Oregon has 21 known cases of COVID-19 in 10 counties, with the largest concentration in Washington County, where eight people have tested positive for the virus. But testing has been severely limited and the disease is believed to be circulating more widely in many Oregon communities.

Brown said in her Wednesday night announcement, made shortly before 10 p.m., that the state health authority has expanded access to testing for the contagious virus that is particularly deadly to elderly people and those with underlying health conditions. She said that doctors at clinics can order tests from commercial laboratories at their discretion, without state authorization.

She said the state has reached agreements with five hospital systems to test Oregonians for COVID-19. And she said health care providers are no longer required to wear N95 mask to collect samples for testing, which was another barrier. Workers will only be required to wear a regular mask, gown, gloves and eye protections, which she said will make testing simpler for health care workers and easier for patients to obtain.

Brown said that events and gatherings at which people can remain at least three feet apart are still permitted.

-- Betsy Hammond; betsyhammond@oregonian.com; @OregonianPol

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