The Oregon Health Authority has declared a measles outbreak after confirming five cases statewide since January 1, 2026, with cases identified in Clackamas and Linn counties. The Clackamas County cases included exposure sites at healthcare facilities, including Kaiser Permanente Sunnyside Center and a medical center in Oregon City. All three initial cases — two in Linn County and one in Clackamas — involved unvaccinated individuals. OHA officials stated these confirmed cases "likely represent only a portion of infections occurring statewide."

The outbreak arrives against the backdrop of the worst national measles surge in more than three decades. The U.S. recorded 2,283 confirmed measles cases in 2025 — a 34-year high — and as of March 5, 2026, another 1,281 cases have been confirmed nationally, with 93% occurring in unvaccinated individuals. Oregon's own vulnerability is measurable: a record 9.7% of kindergartners claimed nonmedical vaccine exemptions in the 2024-2025 school year, the highest rate ever recorded. Overall kindergarten vaccination rates have fallen to 86.3% — well below the 95% threshold needed for herd immunity against measles. Oregon ranks among the top five states nationally for nonmedical exemption rates, behind Idaho, Alaska, and Utah.

For Oregon providers and health systems, the outbreak means immediate operational burden: contact tracing, post-exposure prophylaxis (MMR vaccine within 72 hours or immunoglobulin within six days), and isolation protocols. OHA launched a new wastewater surveillance dashboard in February 2026, which detected low-level measles virus in nine Oregon counties — including Multnomah, Marion, Yamhill, Deschutes, and Douglas — suggesting broader circulation than confirmed case counts indicate. The wastewater data, covering two-week periods since October 2025, provides an early warning system but also underscores how much transmission may be going undetected.

Watch for whether OHA and the Legislature revisit Oregon's permissive nonmedical exemption laws. With vaccination rates declining for three consecutive years and a declared outbreak underway, the political environment may shift. Key questions: whether the Western Health Alliance issues coordinated childhood vaccination guidance that diverges from federal recommendations, and whether Clackamas County's exposure sites at healthcare facilities prompt new infection control protocols for outpatient clinics. The wastewater dashboard bears close monitoring — if measles virus levels escalate from "low" to "moderate" in Portland-area counties, a broader public health response will be needed.