Result from new study of a hypothetical cohort of 4990 college-age students & 10 undetected cases of SARS-CoV-2: “We identified no circumstance in this modelling study under which symptom-based screening alone would be sufficient to contain an outbreak.” https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2768923

“We adapted a simple compartmental epidemic model to capture the essential features of the situation facing university decision-makers...” The authors made a publicly accessible version of the model implementation available here: https://docs.google.com/spreadsheets/u/0/d/1otD4h-DpmAmh4dUAM4favTjbsly3t5z-OXOtFSbF1lY/htmlview#gid=1783644071

“We assumed that after a lag of 8 hours, individuals receiving a positive test result (true or false) and those exhibiting COVID-19 symptoms would be moved from the general population to an isolation dormitory... and from which no further transmissions would occur.”

“We assumed a mean time from exposure to both infectiousness and screening detectability of 3 days, a symptomatic case fatality risk of 0.05%, and a 30% probability that infection would eventually lead to observable COVID-19–defining symptoms in this young cohort.”

Effect of test frequency: “During an 80-day semester in the base case (ie, Rt of 2.5 and 10 exogenous infections each week), screening every 1, 2, 3, or 7 days with a 70% sensitive, 98% specific test resulted in 162, 243, 379, and 1840 cumulative infections, respectively.”

“Of the many uncertain variables driving our assessment of the required frequency of screening, we highlight Rt. This uncertain measure of the transmission potential of infection will depend in part on factors that are within the control of students & university administrators.”

“Even with a 98% specific screening test, false-positive results will present a challenge. Until a confirmatory test result is obtained, anyone receiving a positive test result will be presumed to be infectious and need to be separated from other students.”

“Obtaining an adequate supply of testing equipment will be a challenge. On a college campus with 5000 enrollees, screening students alone every 2 days will require more than 195 000 test kits during the abbreviated semester.”

“The simple model underlying this analysis has notable limitations. We assumed homogenous mixing without age-dependent transmission. We did not explicitly include the effect of screening on faculty & staff...We assumed that no students arrive on campus with immunity to COVID-19.”

“While this analysis offers guidance on the frequency of screening, it does not speak to the logistic challenges of deploying testing strategies on large college campuses. Such challenges include the acquisition of supplies; the orchestration of screening at scale...”

“... the monitoring of adherence; the development of a strategy for rapid result return, contact, and isolation; and the availability and maintenance of an isolation dormitory with all single rooms and bathrooms.”

“In this study, screening every 2 days using a rapid, inexpensive, and even poorly sensitive (>70%) test, coupled with strict interventions that keep Rt less than 2.5, was estimated to yield a modest number of containable infections and to be cost-effective.”