Background To improve understanding of the antibody response to SARS-CoV-2 infection, we examined seroprevalence, incidence of infection, and seroconversion among a cohort of young adults living on university campuses during the fall of 2020. Methods At the beginning (semester start) and end (semester end) of an 11-week period, serum collected from 107 students was tested using the qualitative Abbott Architect SARS-CoV-2 IgG and AdviseDx SARS-CoV-2 IgG II assays. Results were matched to interim weekly surveillance viral testing and symptom data. Results With the SARS-CoV-2 IgG assay, 15 (14.0%) students were seropositive at semester start; 29 (27.1%) students were seropositive at semester end; 10 (9.3%) were seropositive at both times. With the AdviseDx SARS-CoV-2 IgG II assay, 17 (16.3%) students were seropositive at semester start, 37 (35.6%) were seropositive at semester end, and 16 (15.3%) were seropositive at both times. Overall, 23 students (21.5%) had positive viral tests during the semester. Infection was identified by serial testing in a large majority of individuals who seroconverted using both assays. Those seropositive at semester end more frequently reported symptomatic infections (56.5%) than asymptomatic infections (30.4%). Conclusion Differences between antibody targets were observed, with more declines in antibody index values below the threshold of positivity with the anti-nucleocapsid assay compared to the anti-spike assay. Serology testing, combined with serial viral testing, can detect seroconversions, and help understand the potential correlates of protection provided by antibodies to SARS-CoV-2.

OBJECTIVECharacterize college student COVID-19 behaviors and attitudes during the early pandemic. Participants: Students on two university campuses in Wisconsin.METHODSSurveys administered in September and November 2020.RESULTSFew students (3-19%) participated in most in-person activities during the semester, with eating at restaurants as the exception (72-80%) and attending work (35%) and parties (33%) also reported more frequently. The majority wore masks in public (94-99%), but comparatively fewer (42%) did so at parties. Mask-wearing at parties decreased from September to November (p < 0.05). Students attending parties, or consuming more alcohol, were less concerned and more likely to take COVID-19-associated risks.CONCLUSIONSStudents were motivated to adhere to COVID-19 prevention measures but gathered socially. Though there was frequent public masking, mask-wearing at parties declined in November and may represent pandemic fatigue. High-yield strategies for decreasing viral spread may include changing masking social norms and engaging with students about creative risk-reduction strategies.

Antigen-based tests for SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), are inexpensive and can return results within 15 minutes (1). Antigen tests have received Food and Drug Administration (FDA) Emergency Use Authorization (EUA) for use in asymptomatic and symptomatic persons within the first 5-12 days after symptom onset (2). These tests have been used at U.S. colleges and universities and other congregate settings (e.g., nursing homes and correctional and detention facilities), where serial testing of asymptomatic persons might facilitate early case identification (3-5). However, test performance data from symptomatic and asymptomatic persons are limited. This investigation evaluated performance of the Sofia SARS Antigen Fluorescent Immunoassay (FIA) (Quidel Corporation) compared with real-time reverse transcription-polymerase chain reaction (RT-PCR) for SARS-CoV-2 detection among asymptomatic and symptomatic persons at two universities in Wisconsin. During September 28-October 9, a total of 1,098 paired nasal swabs were tested using the Sofia SARS Antigen FIA and real-time RT-PCR. Virus culture was attempted on all antigen-positive or real-time RT-PCR-positive specimens. Among 871 (79%) paired swabs from asymptomatic participants, the antigen test sensitivity was 41.2%, specificity was 98.4%, and in this population the estimated positive predictive value (PPV) was 33.3%, and negative predictive value (NPV) was 98.8%. Antigen test performance was improved among 227 (21%) paired swabs from participants who reported one or more symptoms at specimen collection (sensitivity = 80.0%; specificity = 98.9%; PPV = 94.1%; NPV = 95.9%). Virus was isolated from 34 (46.6%) of 73 antigen-positive or real-time RT-PCR-positive nasal swab specimens, including two of 18 that were antigen-negative and real-time RT-PCR-positive (false-negatives). The advantages of antigen tests such as low cost and rapid turnaround might allow for rapid identification of infectious persons. However, these advantages need to be balanced against lower sensitivity and lower PPV, especially among asymptomatic persons. Confirmatory testing with an FDA-authorized nucleic acid amplification test (NAAT), such as RT-PCR, should be considered after negative antigen test results in symptomatic persons, and after positive antigen test results in asymptomatic persons (1).

Background. Multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreaks occurred at universities during Fall 2020, but little is known about risk factors for campus-associated infections or immunity provided by anti-SARS-CoV-2 antibodies in young adults. Methods. We conducted surveys and serology tests among students living in dormitories in September and November to examine infection risk factors and antibody presence. Using campus weekly reverse-transcription polymerase chain reaction (RT-PCR) test results, the relationship between survey responses, SARS-CoV-2 antibodies, and infections was assessed. Results. Of 6136 students, 1197 completed the survey and 572 also completed serologic testing in September compared with 517 and 414 in November, respectively. Participation in fraternity or sorority events (adjusted risk ratio [aRR], 1.9 [95% confidence interval {CI}, 1.4-2.5]) and frequent alcohol consumption (aRR, 1.6 [95% CI, 1.2-2.2]) were associated with SARS-CoV-2 infection. Mask wearing during social events (aRR, 0.6 [95% CI, .6-1.0]) was associated with decreased risk. None of the 20 students with antibodies in September tested positive for SARS-CoV-2 during the semester, while 27.8% of students who tested RT-PCR positive tested negative for antibodies in November. Conclusions. Frequent drinking and attending social events were associated with SARS-CoV-2 infection. Antibody presence in September appeared to be protective from reinfection, but this finding was not statistically significant.

Abstract Background Real-time reverse transcription polymerase chain reaction (rRT-PCR) and antigen tests are important diagnostics for SARS-CoV-2. Sensitivity of antigen tests has been shown to be lower than that of rRT-PCR; however, data to evaluate epidemiologic characteristics that affect test performance are limited. Methods Paired mid-turbinate nasal swabs were collected from university students and staff and tested for SARS-CoV-2 using both Quidel Sofia SARS Antigen Fluorescent Immunoassay (FIA) and rRT-PCR assay. Specimens positive by either rRT-PCR or antigen FIA were placed in viral culture and tested for subgenomic RNA (sgRNA). Logistic regression models were used to evaluate characteristics associated with antigen results, rRT-PCR cycle threshold (Ct) values, sgRNA, and viral culture. Results Antigen FIA sensitivity was 78.9% and 43.8% among symptomatic and asymptomatic participants respectively. Among rRT-PCR positive participants, negative antigen results were more likely among asymptomatic participants (OR 4.6, CI:1.3-15.4) and less likely among participants reporting nasal congestion (OR 0.1, CI:0.03-0.8). rRT-PCR-positive specimens with higher Ct values (OR 0.5, CI:0.4-0.8) were less likely, and specimens positive for sgRNA (OR 10.2, CI:1.6-65.0) more likely, to yield positive virus isolation. Antigen testing was >90% positive in specimens with Ct values <29. Positive predictive value of antigen test for positive viral culture (57.7%) was similar to that of rRT-PCR (59.3%). Conclusions SARS-CoV-2 antigen test advantages include low cost, wide availability and rapid turnaround time, making them important screening tests. The performance of antigen tests may vary with patient characteristics, so performance characteristics should be accounted for when designing testing strategies and interpreting results.

Real-time reverse transcription polymerase chain reaction (rRT-PCR) and antigen tests are important diagnostics for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Sensitivity of antigen tests has been shown to be lower than that of rRT-PCR; however, data to evaluate epidemiologic characteristics that affect test performance are limited. Paired mid-turbinate nasal swabs were collected from university students and staff and tested for SARS-CoV-2 using both Quidel Sofia SARS Antigen Fluorescent Immunoassay (FIA) and rRT-PCR assay. Specimens positive by either rRT-PCR or antigen FIA were placed in viral culture and tested for subgenomic RNA (sgRNA). Logistic regression models were used to evaluate characteristics associated with antigen results, rRT-PCR cycle threshold (Ct) values, sgRNA, and viral culture. Antigen FIA sensitivity was 78.9% and 43.8% among symptomatic and asymptomatic participants, respectively. Among rRT-PCR positive participants, negative antigen results were more likely among asymptomatic participants (odds ratio [OR] 4.6, 95% confidence interval [CI]: 1.3–15.4) and less likely among participants reporting nasal congestion (OR 0.1, 95% CI: .03–.8). rRT-PCR-positive specimens with higher Ct values (OR 0.5, 95% CI: .4–.8) were less likely, and specimens positive for sgRNA (OR 10.2, 95% CI: 1.6–65.0) more likely, to yield positive virus isolation. Antigen testing was >90% positive in specimens with Ct values < 29. Positive predictive value of antigen test for positive viral culture (57.7%) was similar to that of rRT-PCR (59.3%). SARS-CoV-2 antigen test advantages include low cost, wide availability and rapid turnaround time, making them important screening tests. The performance of antigen tests may vary with patient characteristics, so performance characteristics should be accounted for when designing testing strategies and interpreting results.

University settings have demonstrated potential for COVID-19 outbreaks, as they can combine congregate living, substantial social activity, and a young population predisposed to mild illness. Using genomic and epidemiologic data, we describe a COVID-19 outbreak at the University of Wisconsin (UW)-Madison. During August - October 2020, 3,485 students tested positive, including 856/6,162 students living in residence halls. Case counts began rising during move-in week for on-campus students (August 25-31, 2020), then rose rapidly during September 1-11, 2020. UW-Madison initiated multiple prevention efforts, including quarantining two residence halls; a subsequent decline in cases was observed. Genomic surveillance of cases from Dane County, where UW-Madison is located, did not find evidence of transmission from a large cluster of cases in the two residence halls quarantined during the outbreak. Coordinated implementation of prevention measures can effectively reduce SARS-CoV-2 spread in university settings and may limit spillover to the community surrounding the university.

University settings have demonstrated potential for coronavirus disease (COVID-19) outbreaks; they combine congregate living, substantial social activity, and a young population predisposed to mild illness. Using genomic and epidemiologic data, we describe a COVID-19 outbreak at the University of Wisconsin–Madison, Madison, Wisconsin, USA. During August–October 2020, a total of 3,485 students, including 856/6,162 students living in dormitories, tested positive. Case counts began rising during move-in week, August 25–31, 2020, then rose rapidly during September 1–11, 2020. The university initiated multiple prevention efforts, including quarantining 2 dormitories; a subsequent decline in cases was observed. Genomic surveillance of cases from Dane County, in which the university is located, did not find evidence of transmission from a large cluster of cases in the 2 quarantined dorms during the outbreak. Coordinated implementation of prevention measures can reduce COVID-19 spread in university settings and may limit spillover to the surrounding community.

During July 2-August 11, 2020, an outbreak of coronavirus disease 2019 (COVID-19) occurred at a boys' overnight summer school retreat in Wisconsin. The retreat included 152 high school-aged boys, counselors, and staff members from 21 states and territories and two foreign countries. All attendees were required to provide documentation of either a positive serologic test result* within the past 3 months or a negative reverse transcription-polymerase chain reaction (RT-PCR) tests result for SARS-CoV-2 (the virus that causes COVID-19) ≤7 days before travel, to self-quarantine within their households for 7 days before travel, and to wear masks during travel. On July 15, the Wisconsin Department of Health Services (WDHS) began an investigation after being notified that two students at the retreat had received positive SARS-CoV-2 RT-PCR test results. WDHS offered RT-PCR testing to attendees on July 28 and serologic testing on August 5 and 6. Seventy-eight (51%) attendees received positive RT-PCR results (confirmed cases), and 38 (25%) met clinical criteria for COVID-19 without a positive RT-PCR result (probable cases). By the end of the retreat, 118 (78%) persons had received a positive serologic test result. Among 24 attendees with a documented positive serologic test result before the retreat, all received negative RT-PCR results. After RT-PCR testing on July 28, WDHS recommended that remaining susceptible persons (asymptomatic and with negative RT-PCR test results) quarantine from other students and staff members at the retreat. Recommended end dates for isolation or quarantine were based on established guidance (1,2) and determined in coordination with CDC. All attendees were cleared for interstate and commercial air travel to return home on August 11. This outbreak investigation documented rapid spread of SARS-CoV-2, likely from a single student, among adolescents and young adults in a congregate setting. Mitigation plans that include prearrival quarantine and testing, cohorting, symptom monitoring, early identification and isolation of cases, mask use, enhanced hygiene and disinfection practices, and maximal outdoor programming are necessary to prevent COVID-19 outbreaks in these settings (3,4).