(Portland, OR) -- The COVID-19 mass vaccination clinic at the Oregon Convention Center will start taking walk-ins without appointments today. The clinic isn't normally open on Fridays, but they'll be open from 9 a.m. to 4 p.m. They'll be closed Saturday and Sunday. They'll return to normal hours on Monday. They prefer that people make appointments at the All 4 Oregon website. They hope the ability to offer walk-in vaccinations will make it easier for people who can't make an appointment.