s mornings now often start at 4 a.m., scanning the contents of undergraduates feces. Specifically, scanning the data on how much coronavirus they flushed into the shadows, destined to be extracted from 17 manholes connected to dorm buildings on Colorado State Universitys Fort Collins campus.
There are quite extensive numbers of poop jokes, said Wilusz, a CSU molecular biologist.
Emerging research infected people start shedding the coronavirus in their poop early in their infection, and possibly they begin shedding it from their mouths and noses. It means that we can catch them before theyre actually spreading the infection, she said.
In normal times, Wilusz studies stem cells and muscular dystrophy. Now, her team is on the front lines of defense against the massive COVID-19 outbreaks that, for a campus with 23,000 undergraduates alone, always seem to be lurking around the corner. The sewage review is part of a multipronged attack that includes the usual weapon of contact tracing plus a specialized paired pooling form of testing saliva samples. So far, the school has had about 500 cases since the semester started, that of the only somewhat bigger University of Colorado-Boulder.
Amid scientific recommendations and a virus that still holds uncertainties, colleges across the country are taking a choose-your-own-adventure approach to COVID-19. For those holding in-person classes, the adventure includes an extra puzzle: how to concentrate a lot of people into one place without an outbreak tearing through the student body and spilling into the community, all without safety precautions that would break the bank. Testing is at the core of those plans.
A lot of these institutions started testing just symptomatic students. And that is really not good, to put it bluntly, because as weve seen over the past couple of months, students tend to be asymptomatic, said , an assistant professor at Davidson College in North Carolina who is leading tracking how universities are responding to the pandemic. The institutions that have been the most successful are ones that are testing every student at least once a week.
According to data collected in mid-September, only about 6% of large universities with in-person classes are routinely testing all students, according to an of his groups data. The University of Illinois at Urbana-Champaign has been leading the pack, testing about 10,000 students each day using a . But its pricey. Despite driving down the cost of an individual test to about $10, , a chemist leading the effort, said the school is still spending about $1 million a week.
At Colorado State University, , co-chair of the schools pandemic response team, said initially the school was paying $93 a pop to test students using the usual nose swab method.
We quickly spent several million dollars on testing, said Lynn, who added that cost is just one limiting factor. We cant test everybody in the community, you know, weekly or twice a week.
Instead, a CSU molecular biologist and immunologist who typically studies , said his group recently figured out how to screen saliva for less than $20 a person. It involves pooling drool samples in a strategic way reminiscent of the childrens game Battleship.
Traditionally, involves mixing samples from multiple people and testing them all in one go, to save time and materials. If the pool comes back negative for the virus, everyone in the pool can be considered negative. If its positive, samples from each person in that pool must be retested. If there are high rates of infection, that means a .
Instead of pooling samples willy-nilly, Zabel and his colleagues are doing something he calls paired pooling: They start with an eight-by-eight grid of saliva from 64 people, arrayed almost like a Battleship board. Each persons spit sample gets divided up and analyzed in two pools, one pool for the row it sits in and one for the column it sits in, for a grand total of 16 pools per grid.
If the test containing samples in Row A and the test containing samples from Column One appear positive, that would indicate that the person whose spit is in the A-1 slot is a positive case.
So, its super easy if weve got one positive among 64, said Zabel. In that case, theyve screened 64 people with just 16 tests. No retesting necessary.
Limited retesting is needed only if at least four pools come back positive.
Theyre also using a than usual, in an effort to avoid competing for limited reagents, whose shortages have hampered labs nationwide.
Zabel said it takes between eight and 24 hours for results. However, some drawbacks exist. If retesting is necessary, total turnaround time could extend to three days. And if the outbreak were to grow beyond a certain point, in which at least 5% of people tested are positive, the process would become more cumbersome because theyd have to add more layers of testing.
Its a shifting target and the university is continually reevaluating its testing strategy, but Zabel expects his lab could test up to 3,000 people a day, which would enable testing the entire student body every other week.
According to other researchers, that might not be enough.
and others in the New England Journal of Medicine said its time to ditch any approach that relies on highly accurate tests, and instead embrace antigen tests, which are cheap and quick albeit less accurate and can be administered frequently.
You have the science of testing, which says if youre testing everybody twice a week, you should basically have zero cases, said Larremore, a computational biologist at the University of Colorado-Boulder, referring to modeling studies from his lab and .
But then, theres reality. And no testing system alone will solve the problem, Larremore said, because there are humans involved.
Wilusz, the CSU professor, knows how difficult this is. Often people continue shedding virus in their poop long after theyve recovered, so over the course of the semester more and more dorms have started to yield virus-positive sewage.
And then theres also, we cant stop students pooping in the wrong dorm. So one could poop in this dorm one day and then next door on the other day, she said, making it hard to know which dorm to screen with saliva tests.
Also, only about 5,000 of the schools 28,000 enrolled students live in dorms, though Wilusz said those close quarters create a high risk for spreading the disease because theyre essentially like nursing homes for young people.
She wonders how long students will remain game to spit into tubes before they get bored. Michigan State University researchers experimenting with paired pooling and saliva have made a habit of double-checking that students have submitted spit instead of something else. (Chewing tobacco and something the color of blue Gatorade have sullied a few CSU samples so far.)
But the shifting, multifaceted approach does seem to be helping at Colorado State. Back in September, Wilusz noticed a concerning spike in the amount of virus in the sewage connected to two dorms that collectively housed about 900 students. The university put the dorms on lockdown and tested everyone inside, revealing nine positive cases that hadnt been found using other methods.
Now, with pooled-spit screening, Zabel said the team has been able to identify positives without locking down entire dorms, and can then use subsiding levels in sewage to confirm no infections slipped through the cracks.
The goal is to make it to Thanksgiving, when students return home. But then comes 2021. Well see if we can keep on top of it, Zabel said, knocking on his desk for luck.
