Wastewater Data Shows San Diego County COVID Viral Load Flushing Away, For Now

Wastewater data accurately predicted the Delta and Omicron surges. Current trends are positive, but there are surges in Europe and China, which historically served as precursors to what happens in the U.S.

NBC Universal, Inc.

New information from county wastewater data shows reported COVID cases and viral load in wastewater have taken a dramatic drop since the Omicron variant peak in January.

Updated data provided by the UC San Diego School of Medicine shows the reported number of cases based on wastewater samples taken from the Point Loma pump station dropped to 437 per 100,000 residents as of March 14.

Compare that to 17,507 cases per 100,000 residents reported at the peak of the Omicron surge on Jan. 8.

UC San Diego has been monitoring wastewater since the summer of 2020 and accurately predicted both the Delta and Omicron surge weeks before cases were clinically proven.

Meanwhile, the CDC has gathered data on SARS-CoV-2 RNA levels in wastewater at monitoring sites across the United States.

San Diego County showed a 94% decrease in viral COVID load between Feb. 27 and March 12, according to the CDC.

The positive trends are being mirrored at local hospitals.

"Our volumes are down, our ED visits related to COVID are down, our positivity rate of all the tests that we do is down,” said Brett McClain, Executive Vice President and COO of Sharp Healthcare.

McClain says all Sharp patients are tested for COVID. During the most recent surge, 40% of all tests came back positive. The current positivity rate is under 4%.

McClain said Sharp combines wastewater data with current hospital data to modify operations, which include visitation restrictions, elective surgery decisions and even locations for administrative meetings.

The hospital has created its own internal monitoring system with four levels: minimal, moderate, substantial and widespread. The current level is considered moderate.

While current COVID trends are positive, there are surges in Europe and China, which historically served as a precursor to what happens in the U.S.

“We’ve seen it before, and so we have to remain vigilant on the things we know protect us all, and top of the list is those vaccines and those boosters,” said McClain, who also strongly encourages handwashing and mask wearing.

Meanwhile, the COVID positivity rate was at 3.7 per 100,000 residents as of March 15, according to county data. In January during the Omicron peak, the case rate was 26.4.

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