Frequency of screening is more important than the accuracy of the test
FRIDAY, July 31, 2020 (HealthDay News) — Symptom-based screening alone is not sufficient to contain a COVID-19 outbreak on college campuses, according to a study published online July 31 in JAMA Network Open.
A. David Paltiel, Ph.D., from the Yale School of Public Health in New Haven, Connecticut, and colleagues performed an analytic modeling study that included a hypothetical cohort of 4,990 students without severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and 10 with undetected, asymptomatic SARS-CoV-2 infection at the start of the semester. Screening performance standards were evaluated.
The researchers found that assuming reproductive numbers of 2.5 and daily screening with 70 percent sensitivity, a test with 98 percent specificity yielded 162 cumulative student infections and a mean isolation dormitory daily census of 116 with 21 true-positive students (18 percent). Reducing screening to every two days resulted in 243 cumulative infections and a mean daily isolation census of 76, with 28 true-positive students (37 percent). In the last scenario, decreasing screening to every seven days yielded 1,840 cumulative infections and a mean daily isolation census of 121 students, with 108 true-positive students (90 percent). Test frequency was more strongly associated with cumulative infection than test sensitivity across all scenarios. Symptom-based screening alone was not sufficient to contain an outbreak under any of the scenarios. For a reproductive number of 2.5, 3.5, or 1.5, respectively, testing every two, one, or seven days was most cost-effective, with screening costs of $470, $910, or $120, respectively, per student per semester.
“The safe reopening of campuses in fall 2020 may require screening every two days, uncompromising vigilance, and continuous attention to good prevention practices,” the authors write.
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