CDC: Early evidence of Omicron in community wastewater

Editor's Note

This study by researchers from the Centers for Disease Control and Prevention (CDC) finds that wastewater surveillance programs in four states were the first to detect evidence of Omicron in community wastewater.

California: Omicron was detected in samples collected November 25 and 30, 2021, in two Northern communities. Results from these samples were available December 2. At that time, two cases had been identified in California, but none in those two communities. By December 17, Omicron was found in 145 samples from all 10 sewersheds in California.

Colorado: 13 sewershed samples with Omicron were found on December 2, 2021. At that time only one travel-associated case had been reported. Omicron was not detected in samples collected December 6, but by December 16, it was found at 19 of 21 sewersheds.

New York City: 12 sewershed samples with Omicron were detected on November 21. By December 4, one Omicron case had been identified in a resident of the sewershed area. Samples collected on November 28 from this and another sewershed contained Omicron, as reported to the health department on December 17.

Houston, Texas: 6 sewershed samples of Omicron were found on November 29 from 7 sewersheds across the city. The first clinical detection was reported on December 1. The number of Omicron-positive sites and samples detected increased over the next 2 weeks.

The detection of Omicron in community wastewater provides strong early evidence that the variant was likely present or more widely distributed in these four states than originally indicated by clinical testing alone, the researchers say.