OHA declared a measles outbreak after confirming five cases. The first Clackamas case was confirmed January 16, with a second linked to a new exposure site January 28. Exposure sites include an Oregon City medical center. Wastewater surveillance detected low levels in six counties.

Nearly 10% of kindergarteners received nonmedical exemptions — the highest ever. Only 90.5% have both MMR doses, below the 95% herd immunity threshold. Four of five confirmed cases were unvaccinated.

The outbreak comes as the federal government has weakened vaccine messaging. The CDC's revised schedule has sowed confusion among parents.

Watch for: Whether case counts climb as wastewater suggests broader circulation. OHA's school exemption deadline this spring is a critical inflection point. If the outbreak intensifies, expect renewed discussion about tightening Oregon's permissive nonmedical exemption law. Two doses of MMR remain 97% effective — this is an entirely preventable crisis.