Screening Programs for SARS-CoV-2 Infections on a University Campus — Austin, Texas, September 30–November 30, 2020

Colleges and universities in the United States have relied on various measures during the COVID-19 pandemic to prevent transmission of SARS-CoV-2, the virus that causes COVID-19, including implementing testing programs (1–3). These programs have permitted a safer return to campus for students by identifying infected persons and temporarily isolating them from the campus population (2,3). The University of Texas at Austin (UT Austin) implemented COVID-19 prevention measures in Fall 2020* including the following testing programs: clinic-based diagnostic testing, voluntary community screening, and targeted screening (testing of specific student populations in situations of increased transmission risk). During September 30–November 30, 2020, UT Austin students participated in tests for SARS-CoV-2, which resulted in the detection of 401 unique student cases of COVID-19 from among 32,401 tests conducted.^† Among students who participated in one targeted screening program for students attending campus events, 18 (37.5%) of 48 infected students were asymptomatic at the time of their positive test result compared with 45 (23%) of 195 students identified through community testing and nine (5.8%) of 158 students identified through clinic-based testing. Targeted screening also identified a different population of students than did clinic-based and community testing programs. Infected students tested through targeted screening were more likely to be non-Hispanic White persons (chi square = 20.42; p<0.03), less likely to engage in public health measures, and more likely to have had interactions in settings where the risk for SARS-CoV-2 transmission is higher, such as restaurants, gyms, and residence halls. In addition to clinic-based SARS-CoV-2 testing at colleges and universities, complementary testing programs such as community and targeted screening might enhance efforts to identify and control SARS-CoV-2 transmission, especially among asymptomatic persons and disproportionately affected populations that might not otherwise be reached.

During September 30–November 30, 2020, UT Austin employed the following SARS-CoV-2 testing programs: 1) clinic-based diagnostic testing administered by University Health Services for persons who were symptomatic or reported exposure to SARS-CoV-2 (clinic-based testing); 2) Proactive Community Testing, which involved voluntary screening of asymptomatic persons offered at several fixed or rotating sites on-and-off campus (community testing); and 3) targeted screening of specific student populations in situations of increased transmission risk. One targeted screening program focused on Big Ticket holders, students with season tickets to athletic events. These events are large gatherings that might involve several SARS-CoV-2 infection risk factors such as several hours of possible exposure, the potential for crowding, and behaviors such as singing and shouting.^§ Students were tested up to 3 days before each event. Either a negative test result or proof of previous SARS-CoV-2 infection 14–90 days before the event was required for entry. Community testing and targeted screening programs were provided to students at no cost; clinic-based tests were billed to students’ insurance. Cases were identified through clinic-based testing using SARS-CoV-2 nucleic acid amplification tests (NAATs), including reverse transcription–polymerase chain reaction (RT-PCR) or isothermal NAAT (ID NOW [Abbott] or Aptima SARS-CoV-2 Assay [Hologic]). Community testing used a Clinical Laboratory Improvement Amendments (CLIA)-certified RT-PCR test performed at a UT laboratory, and testing for Big Ticket holders used an antigen test (Sofia SARS Antigen Fluorescent Immunoassay [Quidel Corporation])^¶ or UT’s CLIA-certified RT-PCR test. Test results were reported to Dell Medical School at UT Austin, which was delegated by Austin Public Health to conduct contact tracing. Contact tracers interviewed infected persons to identify close contacts** during their infectious period,^†† and collected exposure details, including dates, proximity, location, duration of exposure, and mask use. Characteristics, symptom status, isolation practices, and case investigation outcomes among students with COVID-19 were assessed; statistical comparisons among cases identified by the different testing programs were performed using chi square tests or one-way ANOVA in Python (version 3.7.9; Python Software Foundation) using the SciPy statistical package (version 1.5.4; Python Software Foundation); p values <0.05 were considered statistically significant. This study was reviewed by a UT Institutional Review Board and deemed to not be human subjects research. This activity was reviewed by CDC and conducted consistent with applicable federal law and CDC policy.^§§

Among 32,401 tests of UT Austin students, 401 unique COVID-19 cases were identified (Table 1); 3,044 tests were done through clinic-based testing, 25,042 through community testing, and 4,314 through testing of Big Ticket holders. Among one targeted screening program for Big Ticket holders, 75% of infected students self-identified as non-Hispanic White persons, compared with 48.7% of infected students detected by community testing and 58.9% of infected students detected by clinic-based testing (chi square = 20.42; p<0.03). The proportion of non-Hispanic White students identified by each of the three testing programs was higher than that reported for the overall UT Austin student population^¶¶ (38.9%; chi square = 177; p<0.001). UT contact tracers interviewed 85.5% of all infected persons. Among Big Ticket holders, 75% of infected persons were interviewed, 20.8% were unreachable by phone, and 4.2% stated they were unwilling to participate in the interview, a larger proportion of refusals than for community testing (1.0%) and clinic-based testing (0.6%).

Approximately 38% of cases among Big Ticket holders occurred in persons who were asymptomatic at the time of their positive test results, compared with 23% identified through community testing and 6% through clinic-based testing (chi square = 35; p<0.001). Higher proportions of infected students from the Big Ticket and community testing programs were tested before symptom onset (15.0% and 14.2%, respectively) compared with clinic-based testing (5.5%); however, these differences were not statistically significant. Infected persons detected through testing of Big Ticket holders were less likely to have isolated after receiving a positive result (80%) than were those identified through community (91.2%) and clinic-based testing (97.1%).

Among 195 cases detected through community testing and 48 through testing of Big Ticket holders, 120 (61.5%) and 35 (72.9%) persons, respectively had no previous engagement with community testing (Table 2). Among 40 asymptomatic infected persons who had no previous community testing history, the testing program for Big Ticket holders identified a higher proportion of asymptomatic cases than did community testing (31.4% versus 24.2%; chi square = 7.53; p = 0.02).

A similar average number of close contacts was reported by infected persons identified from testing of Big Ticket holders (2.6 per person), community testing (3.1), and clinic-based testing (2.7) (p = 0.5). The most frequently reported exposure location among all testing programs was household (44%), defined as a shared living space (including a shared room or suite in a residence hall) (Table 3). The second most common exposure location identified through community and clinic-based testing was private residence or apartment visits (24% and 29%, respectively). In contrast, restaurants (22%) and residence halls (16%) were the next most common exposure locations among infected persons identified through testing for Big Ticket holders. These persons also reported a higher proportion of exposures in fitness or recreational facilities (6%) than did persons identified through community testing (3%) and clinic-based testing (1%), and a lower proportion of exposures outdoors (2% versus 13% and 6%, respectively; chi square = 145; p<0.001). Across all programs, most exposures were characterized by one or both students not wearing a mask (91.4% of Big Ticket holders and 87.9% of those who received community and clinic-based testing) (chi square = 1.1; p = 0.3). Contact tracers provided counseling to both infected persons and close contacts on appropriate mask use to prevent future exposures or reinfection.

Acknowledgments

Daniel Iken, Jessica Klima, Luke Klima, Jennifer Sarchet-Morgan, Ta-Shina Williams, Carol Xia, contact tracing staff members and volunteers, UT Health Austin and University Health Services, University of Texas at Austin; Dell Medical School, University of Texas at Austin and UT Health Austin leadership; staff members of University Health Services, University of Texas at Austin; staff members of University of Texas at Austin Athletics.

Corresponding author: Kayleigh Nerhood, [email protected].

¹Dell Medical School, University of Texas at Austin; ²University of Texas at Austin Athletics; ³University Health Services, University of Texas at Austin.

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* Screening targeted to students who held season tickets to athletic events.
^† Population limited to persons who were interviewed.
^§ Population limited to persons who were interviewed and symptomatic.

* Symptom status reported at time of case investigation.
^† Excluding cases detected by the University Health Services clinic-based testing.
^§ Infected persons had at least one COVID-19 test via community testing at any time before their positive result and during the study period.
^¶ Students who held season tickets to athletic events.

* If an infected person and a close contact interacted in multiple locations, contact tracers chose the most likely transmission site based on duration, proximity, ventilation, and mask use.
^† Population limited to persons who were interviewed and named close contacts.
^§ Students who held season tickets to athletic events.