HOUSTON — The Houston Health Department is testing the city's wastewater for the omicron variant of COVID-19.

The city said the variant was not detected in the wastewater samples collected last week.

“Testing wastewater will help us stay fully aware and prepared for the omicron variant presence throughout Houston. This proactive measure by the Houston Health Department is another indication of the City’s dedication to protecting Houstonians,” Mayor Sylvester Turner said. “Although our team has not detected omicron in Houston, we should anticipate it arriving, and the health department is prepared to scale its operations as needed to respond. In the meantime, I encourage eligible Houstonians to get fully vaccinated.”

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There are a lot of unknowns about the omicron variant. Health officials are still trying to determine if it's more transmissible, causes serious illness or evades vaccine protection compared to other variants.

RELATED: Answering your questions about the COVID-19 omicron variant

Health officials have been tracking the spread of COVID-19 through wastewater throughout the coronavirus pandemic.

It helps alert them when an outbreak is on its way.

"The wastewater predicts what's about to happen about two to four weeks ahead of time," Chief Medical Officer for the City of Houston Dr. David Persse said in August.

How do they test the wastewater?

The bottles of wastewater are delivered to a lab at Rice University where it is concentrated, filtered, then genomic material is extracted. It’s also analyzed by the Baylor College of Medicine. Wastewater testing has been used in other parts of the world for disease monitoring and illicit drug use. However, the COVID-19 pandemic is the first time the technique has been used in Houston.

RELATED: Houston Health Department testing wastewater weekly to track COVID-19 variants

Officials said wastewater testing is the best indicator of the spread of COVID-19 in Houston. It’s because when someone’s sick, they shed the virus when they go to the restroom.

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