The modeling data behind Duke’s COVID response plan
In the middle of the fall semester, Duke saw no COVID transmissions traced back to the classroom. This is the result of a COVID response plan that stands out in several ways from other universities: masks in the classroom, full vaccination of faculty, staff and students, and intensive surveillance testing and speed. execution of results.
A month of decline and low numbers of infections shows that the response is working; Last week at the Academic Council, a team of expert faculty and senior executives showed how it works. Speakers presented the modeling data behind their recommendations and how the numbers shaped a plan to safely bring students back to campus and classroom learning in person.
With an article to appear in a leading medical journal, Duke’s efforts are gaining national attention. However, speakers on Thursday did not proclaim victory: The high rates of unvaccinated people in the surrounding community and the risk of new COVID variants present lingering concerns as winter approaches.
There was some optimism, however. “We don’t see any transmission in the classroom. We also don’t see any transmission on the field in athletics. We don’t see a lot of transmission in everyday activities, ”said Dr. Cameron Wolfe, infectious disease specialist at Duke Health. “In clinical settings, we find that the masks have had a significant effect and offer protection. “
The models used by the response team were based in part on a full year of data collected in 2020-2021 when there were fewer unvaccinated students and staff on campus. The success of testing protocols, contact tracing, and social distancing gave the modeling team confidence that the university could safely transition to full in-person learning. But other aspects of the intervention plan were in question.
Surveillance tests are needed
In June, the models were based on the assumption that the campus community would be fully vaccinated and that the vaccine’s effectiveness would be over 90% against COVID.
“What we saw in the numbers is what collective immunity looks like,” said Steve Haase, professor of biology and medicine. “Then the Delta variant arrived. “
While the vaccines continued to be effective against Delta and provided strong protection against serious illness, the effectiveness in reducing infection against Delta fell to around 70%. The model showed that infections on campuses would increase dramatically unless intensive surveillance testing was put in place. All residential undergraduates are now tested twice a week.
In the 2020-21 school year, before vaccines were available, the use of surveillance tests, along with the timeliness of test results, kept infections low.
“This is why we made a commitment in June 2021 to continue surveillance testing of students and the university community,” Haase said. “At the time, we were the only university to do this. Now, many are following suit.
But quarantine is not necessary
Last academic year, quarantining students in close contact with others who tested positive was also a central part of the university’s COVID response. During a semester of mostly in-person learning, heavy and continued use of the quarantine would be a huge disruption for many students.
But the same model that recommended surveillance testing showed that quarantining close contacts was no more effective in reducing infections than increasing the testing schedule of those contacts, Haase said. One of the reasons for this is that the speed of execution of the results allowed the students to be quickly isolated if they were positive.
How COVID is Evolving on Campus
A valuable aspect of Duke’s COVID response is that the team is closely monitoring the changing genetic makeup of the infection. Several variants, mainly the Alpha or California variant, were first seen as early as January 2021.
Delta arrived on campus in week 47 of the test program, in July 2021 and immediately took over. As of week 48, nearly 100 percent of infections have involved the Delta variant.
“It was an extremely quick takeover,” Haase said. “What we are looking at now is to follow the Delta downlines.” Indeed, in recent weeks, as infections have declined, up to 40 percent of infections have involved Delta sublines, signaling an expected evolution of the strain.
Duke and community health
Duke’s response has not only benefited the University community, but has also helped the public health of Durham and the community at large. Haase noted that the university’s weekly positive rate of 0.09% is lower than the 0.2% rate in Durham and 0.3% in Wake. Both county numbers likely imply underreporting of cases, as neither has significant tests on asymptomatic individuals.
As a faculty member teaching in-person classes this year, Haase said the model was designed to guide faculty and students to have as comprehensive an academic and social experience on campus as possible. “The questions I wanted to answer were, ‘How can I deliver a great course while keeping people safe? “And” How to optimize the student experience while ensuring the safety of people? “
A question posed at the board meeting has yet to be answered: Will fans be able to pack Cameron Indoor Stadium for the basketball season this winter? Wolfe said the team is collecting information on ventilation systems and gathering information from a semester of campus events, but a major factor will be the infection trends of the community during the season. .
“At the end of the day, the game is played in a closed, packaged system. What worked for the students last year when they played, what kept them safe was that they were masked and spaced out, ”Wolfe said.
Haase added that the best models predicting infection trends only work for two weeks. “Beyond that, there’s no way to make a good prediction,” Haase said.