RALEIGH, N.C. — Duke University students probably took more COVID-19 tests than academic tests this fall. And that's a big part of why the university was able to offer in-person classes and keep students living in dorms throughout the semester.
Duke's aggressive testing program — which included entry testing, pool testing and frequent surveillance testing — helped limit the spread of the coronavirus among students, according to a case study published Tuesday in the CDC's Morbidity and Mortality Weekly Report. The study was written by a team of Duke professors, researchers and state health officials.
The university tested about 70,000 specimens from more than 10,000 graduate and undergraduate students between Aug. 2 and Oct. 11 for this study. The university identified 84 COVID-19 cases among students, most of whom were asymptomatic, according to the study.
Overall, Duke has administered 162,552 tests to students and employees since Aug. 2, with 217 positive cases, which is a 0.13% positivity rate. In comparison, UNC-Chapel Hill and N.C. State University reported more than 1,000 COVID-19 cases among students during the fall semester.
UNC and NCSU did not require entry testing, but did test students throughout the semester based on contract tracing and for athletics. Both schools moved classes online about a week into the semester and closed dorms because of coronavirus outbreaks on campus.
Duke, which has a smaller student body and limited the number of students living on campus, was able to finish the fall semester with in-person classes and wasn't forced to close dorms.
"With a lot of hard work and a lot of complementary components you can reduce transmission in environments such as campuses," said Dr. Tom Denny, professor and chief operating officer at the Duke Human Vaccine Institute.
That includes mass testing, face mask mandates, reduced campus housing and cooperation from students to limit social gatherings.
Denny said to think of the efforts as a Super Bowl team. There are some star players, but they need to play as a team and coordinate all their skills and efforts to win the championship, he said.
The first thing Duke students did when they came to campus in August was get tested for COVID-19. Then they moved into their dorms. Students were also asked to self-quarantine for 14 days before coming to Duke and told not to come if they tested positive at home.
Duke's asymptomatic testing plan started with researchers modeling who to test and when, which included students returning to campus and moving into dorms. Then, the plan quickly expanded.
The team saw patterns of where positive cases were and the activities of those students and focused on testing heavily in those areas, whether it was multiple floors of a residence hall, in a classroom or at an apartment complex.
The university tried to make it an "educated sampling" and to target the testing to where they would predict a higher risk of a transmission event occurring, Denny said.
In late September, Duke ramped up the program and trained more people to test residential undergraduate students twice weekly, off-campus undergraduate students at least once a week and graduate students like those in the medical and business schools weekly.
At that point, Duke was administering about 15,000 tests per week and up to 2,500 daily.
Students living on campus tested themselves using kits with prelabeled tubes, swabs and specimen bags, which made it easy and convenient. The university also ran 15 testing sites across campus to collect samples from students.
Testing is a marker of what's occurring, and if students were not wearing face masks and following social distancing and gathering rules, then Duke would be seeing high numbers, Denny said.
Most students were following good behavior, and the testing helped Duke pick up early infections and then try to get those individuals into isolation or quarantine and minimize the spread on campus and in the community, he said.
Duke created a smartphone app for students and employees to monitor their symptoms and report potential exposure.
Researchers also developed a unique coronavirus test that doesn't give a positive or negative result, but shows the number of viral particles a person has. That helped determine how contagious a student was, even if they were asymptomatic.
That test was critical in a few cases where students were feeling fine walking around campus and don't know they are sick, but were considered a "potential superspreader," Denny said.
"That's the type of person that is more likely a transmitter than someone who has very little virus," Denny said.
That special test also uses a testing platform or equipment that's not typically used in a clinical laboratory. So, the university bought enough to last through the fall semester and didn't risk running low on supplies like others did. Duke has also already purchased what it needs to get through the spring semester, Denny said.
Duke's testing program also included pool surveillance testing of asymptomatic students and employees, which has been critical to minimizing spread, The News & Observer previously reported.
One student's sample is combined with four other people's samples to be tested and analyzed in a batch. Testing in a batch lowers the cost per test and allows for more tests while saving time and supplies.
If a batch comes back with a positive result, the individual samples are tested separately to identify the source of that positive result.
This method helps the university understand where the virus is on campus, how it's being spread and helps identify potential hotspots.
Multiple universities brought students back this fall with plans to only test individuals with symptoms. Among colleges with in-person classes and approximately 5,000 undergraduates, only 6% routinely tested all of their students in the fall semester, according to the study, which cited an NPR article.
The fact that 51% of COVID-19 infections in this analysis were asymptomatic suggests that a large portion of cases would be missed using that method.
Duke's study shows that college campuses can control the spread with a number of tactics, including mass testing. However, not every university has the infrastructure or financial capacity to pull off what Duke is doing.
Denny said there are components of the testing program that other universities can use to minimize transmission.
For UNC or N.C. State, which have bigger campuses, modeling and following where potential positives are occurring would probably be a more sustainable approach, Denny said.
Both those universities and others in the UNC System are expanding their testing programs this spring and requiring reentry testing for students, faculty and staff.
Many schools won't have access to testing, but they can follow some of the guidelines Duke has set like asking students to self-quarantine and get tested in their hometown before they arrive on campus, Denny said. The testing also needs to be paired with social distancing, mask rules and other common sense public health measures, he said.
Some universities are also opting to offer only single dorm rooms, which Duke did this fall.
"The testing is just the marker of the behavior and all the other successful parts of the program," Denny said. "At the end of the day, they all focus on differing approaches to social distancing in the day-to-day lifestyle."
