Missouri tracking rise of delta variant through wastewater system

COLUMBIA, Mo. — In Missouri, experts say a more contagious strain of Covid-19 is spreading rapidly, particularly in smaller, rural communities where vaccination rates are sluggish.

The delta variant, first detected in India, has been found in the wastewater of at least 10 counties, according to an NBC review of data in the state’s “Sewershed Surveillance Project.”

“Since about the second week of May, we’ve seen a very large increase in the prevalence of the delta variant,” said Dr. Marc Johnson, a professor of molecular microbiology and immunology at the University of Missouri. “And the speed at which it spread is quite amazing. It spread really quickly through the state.”

Johnson, and his colleague Dr. Chung-Ho Lin, a research associate professor and lead scientist in the university’s bioremediation program, have worked with the Missouri Department of Health and Senior Services and the Department of Natural Resources to track the coronavirus through wastewater, with the collaboration beginning last summer.

Johnson’s lab focuses on separating the virus from larger particles of waste and extracting its genetic material. Researchers can amplify the genetic material and study it in greater detail, through a process known as quantitative reverse transcription polymerase chain reaction.

It’s a time-consuming endeavor, but one that experts say can be a highly effective mitigation tool. In addition to detecting the presence of the virus that causes Covid-19 in human waste, researchers are able to identify specific variants.

“It’s just a much more comprehensive way of studying the spread of the virus,” Johnson explained. “When you rely on human testing, you’re relying on people that got tested, have access to health care, and whatnot. Our system will tell you about an entire city without any bias for anything. As long as you use the sewer system, we will detect it.”

Each week, the Department of Health and Senior Services sends the teams at the university from four to 50 boxes of wastewater samples from treatment facilities across the state.

Researchers first detected the delta variant on May 10, in wastewater from Branson. That same week, they found it in wastewater collected some 235 miles away, in Brookfield.

It was the start of a pattern that’s concerned officials. Both Branson and Brookfield are smaller cities, with low vaccination rates, in a state where only 38 percent of residents are fully vaccinated. Nationwide, more than 45 percent of eligible Americans are fully vaccinated.

“We’re not talking about one continuous city. This is lots of small individual communities,” Johnson said. “It’s concerning that it’s spreading so rapidly.”

In Linn County, home of Brookfield, less than a third of residents are fully vaccinated. Linn County’s health administrator, Krista Neblock, told NBC News the vaccination rate and the presence of the delta variant are disconcerting.

“If you would have asked me at the beginning of May if I would have thought at the end of May we would be in the situation that we were in, I would have said no,” she said. “In November, when we weren’t dealing with that variant being in our community, we had maybe one or two members of a household testing positive. But now we have seen whole households test positive, and doing the same mitigation and isolation guidelines that we have been promoting through the whole pandemic.”

Neblock said the delta variant appears to be spreading much faster than previous variants. The Centers for Disease Control and Prevention said last week that the variant is a “variant of concern.” That status applies to a variant when there is reason to believe it is more transmissible, or causes more severe cases or vaccines and treatments are less effective against it.

Neblock said the county’s current wave of Covid-19 cases has led to a hospitalization rate of about 14 percent, and those being hospitalized are younger, 20 to 60 years old, and largely unvaccinated.

“I definitely hope that this surge has opened our community’s eyes a little bit about the importance of the vaccine,” Neblock said.