A sweeping federal vaccine mandate, the details of which were released Thursday, ensures thousands of employees at large Oregon businesses must be vaccinated for COVID-19 or face weekly testing.

But the state’s timeline may differ from the Jan. 4 vaccination deadline laid out in the new federal rules.

Oregon is one of 21 states and Puerto Rico that have their own workplace safety agency. Oregon’s Occupational Health and Safety Division, known as Oregon OSHA, will have 30 days to write its own vaccine rules.

They must be “at least as effective” as the federal rule, but need not be identical — and could be more restrictive.

On Thursday, the state did not commit to matching the national Jan. 4 deadline.

“It is too early yet to say how the timeline will take shape in Oregon,” said Oregon OSHA spokesperson Aaron Corvin.

The state’s homegrown workplace safety program means the federal rule won’t have any effect in Oregon until Oregon OSHA’s own rule is in place.

It’s not clear exactly how many workers will be covered by the state rule once it’s written and adopted.

But assuming it’s similar to the federal rule — which applies to companies with 100 or more employees — about 3 in 5 jobs in Oregon will be covered by a state or federal vaccine mandate, according to the Oregon Employment Department, or about 1.1 million Oregonians. That includes the health care, state government and school workers covered by state mandates that took effect last month.

Also unclear is how the vaccine mandate will be enforced. Oregon OSHA is also the state enforcement agency for workplace health and safety rules. Corvin said the agency expects to take and evaluate complaints much as it does for other workplace rules, but because the state hasn’t yet written its own rules, the specifics remain unclear.

“It is important to understand that our approach will not only be based on enforcement, but also on providing educational, consultation, and technical advice to help employers comply,” Corvin said.

Just over 61% of Oregon adults were fully vaccinated as of Thursday, while 66% have received at least one dose.