Wednesday, 19 January 2022 11:09

Model wastewater tracing program reveals COVID clues

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Houston Health Department employees collect wastewater samples from a manhole. The samples will help the Houston Health Department track viruses such as omicron and other COVID-19 variants around the city. Houston Health Department employees collect wastewater samples from a manhole. The samples will help the Houston Health Department track viruses such as omicron and other COVID-19 variants around the city. Courtesy of Houston Health Department


Being at the forefront of COVID-19 surveillance and data has allowed the Houston Health Department to target lifesaving response activities.

One such activity involves collecting wastewater samples from the city’s 39 treatment facilities and lift stations, which move wastewater from 105 zip codes around the city, and testing them for the virus. The monitoring project was the first of its kind in the country and is being emulated in other cities and states across the nation.

HHD Environmental Science Officer Dr. Loren Hopkins said wastewater can show an increase in the presence of the virus in a particular area of the city.

“It can be a bellwether for what is happening,” Hopkins explained. “It tells us if the viral load is going up or down, or if it’s higher in other places around the city.”

The project showed its effectiveness when Houston began testing for the omicron variant back in November. Genomic sequencing conducted at the HHD laboratory detected the omicron variant in test samples back in December, Hopkins said.

“Through the viral sequence, we were able to tell what type of variant of COVID is here in Houston and where it is,” she said. “We saw it spike out very high. We saw a different sequence from what had been typically seen when everything was the delta variant — a change in the sequence, something not seen in delta — and we knew what to look for in omicron.”

The department has been analyzing wastewater for traces of the COVID-19 virus with support from academic partners Baylor College of Medicine and Rice University, who provide expertise in the fields of virology and environmental engineering, and Houston Public Works.

Hopkins said there had been suggestions that wastewater could be used to help track COVID, but it had never been tried before.

“It was difficult and new, and it’s not HHD’s role to conduct research,” she said.

“We gave the team about five weeks to get good results, or we would do our own research. We worked intensely with our partners, and we wanted to ensure when we got a reading from the lab, it was as accurate as possible.”

Hopkins said during the first peak of the virus in 2020 the team members started having good wastewater data available which allowed them to able to create a system to integrate data into tracking virus in the city and present it to city and infectious disease doctors representing the hospital system.

“We took a sample from the treatment facilities, split it in half and sent them to two separate labs,” she said. “From there, we could tell a finding from the two-lab analysis. It should be close enough to where we could make decisions and have confidence that what we were reporting was reliable. If the finding was erratic, it wouldn’t be useful.”

Hopkins also said Houston is a leader in tracking the virus in wastewater as a public health solution, and she credits the partnerships they have formed for its success.

“We’ve always known how we were going to use the data. Our leaders are very engaged in how to use the data,” she said.

Hopkins said other cities and states do not have grants to provide support to other states to conduct the same research in their communities.

“Although it’s been a burden many cities don’t have as many treatment plants as do, it turned out to be a huge benefit for epidemiology. A lot of people are behind it and our academic partners were willing to drop everything to help us and work on this,” she said.

“They see it’s a real benefit. We’ve refined and used it over time. It’s what has put on the forefront,” Hopkins said. “Also testing for flu, antibody resistance. It’s way more cost effective than analyzing people."

Hopkins said officials look to keep the project in place to continue tracking for new viruses so they are poised to act quickly. She also touted the importance of the partnership with HPW and academics.

“They are crucial. If we didn’t have support from them, we couldn’t do this,”  she said.