MISSION — The Confederated Tribes of the Umatilla Indian Reservation will continue to require masks in all tribal government offices and tribally owned stores and restaurants both on and off the reservation, according to an announcement from tribal health officials.

The announcement comes a week after state and federal health officials said fully vaccinated people don’t need to wear masks in most public settings. State officials later clarified that fully vaccinated Oregonians can only enter a business maskless if they show proof of vaccination, and businesses must require masks if they don’t check.

But the CTUIR decided to keep its previous mask-wearing rules in place because “there is no efficient and reliable method for determining whether a person has been vaccinated,” the announcement said. And although many people have vaccination cards showing they’ve been immunized against COVID-19, tribal officials “will not place the burden on our employees to verify if patrons, co-workers or clients are vaccinated.”

Tribal health officials also said mask rules will remain in place to protect all people within tribal jurisdiction from the coronavirus, particularly those who have yet to be vaccinated.

Tribal officials “strongly” encouraged people intending to hold gatherings during the upcoming graduation season to limit group size and hold gatherings outdoors.

“Any event or gathering that is held, whether in a private social setting or as part of a larger organized event such as prom or graduation, should observe the masking and social distancing requirements that indoor events necessitate,” tribal officials said.

And with the recent case spike on the reservation, tribal health officials said they plan to be “extremely cautious” while considering easing mask requirements in the coming weeks.