The Oregon Health Authority announced 1,635 new known cases of COVID-19 Friday, part of a four-week long decline in infections.

The state also reported a daily positive test rate of 8.4%, the lowest recorded since late December. The rate indicates the percentage of all tests conducted that came back positive for the virus.

Also Friday, the Tigard-Tualatin School District announced that it will no longer require students and staff to wear masks within its buildings starting March 31, the same day the state will stop mandating masks in schools, leaving it to districts to decide. Tigard-Tualatin, with about 11,800 students, is the ninth largest in Oregon.

Big school districts such as Portland, Beaverton and Hillsboro have yet to announce whether they’ll make masks optional or mandatory. Newberg said it’ll strongly recommend but not require masks in its schools starting April 1.

Where the new cases are by county: Baker (12), Benton (47), Clackamas (103), Clatsop (10), Columbia (21), Coos (29), Crook (12), Curry (8), Deschutes (90), Douglas (64), Harney (9), Hood River (15), Jackson (137), Jefferson (4), Josephine (32), Klamath (49), Lake (4), Lane (191), Lincoln (26), Linn (72), Malheur (10), Marion (137), Morrow (3), Multnomah (251), Polk (43), Sherman (1), Tillamook (16), Umatilla (31), Union (8), Wallowa (2), Wasco (10), Washington (163) and Yamhill (25).

Deaths: The state reported 12 people died from causes related to COVID-19:

A 95-year-old man from Union County tested positive Feb. 5 and died Feb. 16 at Grande Ronde Hospital.

An 88-year-old man from Multnomah County tested positive Feb. 13 and died that same day at Adventist Health Portland.

An 82-year-old man from Marion County tested positive Feb. 12 and died Feb. 16 at Salem Hospital.

A 50-year-old woman from Marion County tested positive Feb. 11 and died Feb. 15 at Salem Hospital.

An 88-year-old man from Lane County tested positive Dec. 31 and died Jan. 13 at his residence.

A 69-year-old man from Jackson County tested positive Jan. 20 and died Feb. 16 at Providence Medford Medical Center.

A 92-year-old man from Crook County tested positive Jan. 25 and died Feb. 3 at his residence.

An 84-year-old man from Baker County tested positive Feb. 1 and died Feb. 17 at Saint Alphonsus Medical Center Baker City.

An 87-year-old woman from Douglas County tested positive Jan. 24 and died Feb. 11 at her residence.

A 69-year-old man from Douglas County tested positive Jan. 24 and died that same day at his residence.

A 97-year-old woman from Yamhill County tested positive Jan. 19 and died Feb. 13 at her residence.

An 86-year-old woman from Washington County tested positive Jan. 3 and died Feb. 10 at her residence.

Hospitalizations: 741 people with confirmed coronavirus infections are hospitalized, down 47 since Thursday. That includes 126 people in intensive care, 21 fewer than Thursday.

Since it began: Oregon has reported 685,953 confirmed or presumed infections and 6,456 deaths, among the lowest per capita numbers in the nation. To date, the state has reported 7,328,303 vaccine doses administered, fully vaccinating 2,853,602 people and partially vaccinating 296,100 people.

To see more data and trends, visit https://projects.oregonlive.com/coronavirus/

— Aimee Green; agreen@oregonian.com; @o_aimee