FIG 1.

(A) At OHSU, 12,474 viruses were sequenced with collection dates between October 4, 2020 and December 29, 2021. A total of 1,415 sequences were identified as Alpha, collected between December 29, 2020 and August 30, 2021. There were 6,399 sequences identified as Delta, collected between April 15, 2021 and December 22, 2021. There were 108 sequences identified as Omicron, collected between December 8 and 29, 2021. (B) SGTF appeared concurrently with sequencing-confirmed samples of the Alpha and Omicron variants, with very low levels of SGTF reported in the period of Delta predominance (August through mid-December, 2021). SGTF is defined by samples with S Ct = 0 with N Ct < 30 (dark orange). Samples with S Ct = 0 and N Ct > 30.1 (light orange) or S Ct > 30.1 and N Ct > 30.1 (light blue) were considered nonspecific. Samples with S Ct < 30 and N Ct < 30 (dark blue) were negative for SGTF.