Population

Epidemiology

Clinical history

Testing

Methodology

The methodology for this application comes from the JAMA Network Open article by Paltiel, Zheng, and Walensky (2020). The authors also built a spreadsheet detailing their compartmental model calculations, which can be found online. Our implementation currently reproduced this spreadsheet and may soon expand on it.

Glossary

Sensitivity: The ability of a test, case definition, or surveillance system to identify true cases; the proportion of people with a health condition (or the proportion of outbreaks) that are identified by a screening test or case definition (or surveillance system). See CDC DSEPD Principles of Epidemiology in Public Health Practice.

Specificity: The ability or a test, case definition, or surveillance system to exclude persons without the health condition of interest; the proportion of persons without a health condition that is correctly identified as such by a screening test, case definition, or surveillance system. See CDC DSEPD Principles of Epidemiology in Public Health Practice.

Test cost: The cost of a test to identify occurrence at the individual level even if there is no reason to suspect infection - e.g., there is no known exposure. This includes, but is not limited to, screening of non-symptomatic individuals without known exposure with the intent of making decisions based on the test results. Screening tests are intended to identify infected individuals without, or prior to the development of, symptoms who may be contagious so that measures can be taken to prevent further transmission. See CDC SARS-CoV-2 Diagnostic, Screening, and Surveillance Testing.

Confirmatory test cost: The cost of a test to identify occurrence at the individual level and is performed when there is a reason to suspect that an individual may be infected, such as having symptoms or suspected recent exposure or to determine the resolution of infection. See CDC SARS-CoV-2 Diagnostic, Screening, and Surveillance Testing.

Initial susceptible: Noninfected persons.

Initial infected: Infected, asymptomatic persons.

R0: The reproduction number is the average number of people that one person with COVID-19 is likely to infect in a population without any immunity (from a previous infection) or any interventions. R0 is an estimate of how transmissible a pathogen is in a population. R0 estimates vary across populations and are a function of the duration of contagiousness, the likelihood of infection per contact between a susceptible person and an infectious person, and the contact rate. See CDC COVID-19 Pandemic Planning Scenarios.

Exogenous shocks: Infections transmitted to students by university employees or members of the surrounding community or during superspreader events, such as parties.

Days to Incubation: The mean time from exposure to both infectiousness and screening detectability.

Time to recovery (days): The mean time from confirmed (true-positive) results would remain in the isolation dormitory to ensure they were not infectious before proceeding to a recovered or immune state.

% asymptomatics advancing to symptoms: The probability that infection would eventually lead to observable COVID-19-defining symptoms in the young cohort.

Symptom case fatality risk: The COVID-related mortality in persons of college age.

Time to return FPs from Isolation (days): The time from (false-positive) results would remain isolated, reflecting the assumption that a highly specific confirmatory test could overturn the original diagnosis, permitting them to return to the campus population.

Assumptions

Note: An 80-day time horizon (during an abbreviated 80-day semester, running from Labor Day through Thanksgiving) is used for the analysis.

Note: A target population of younger than 30 years, nonimmune, living students in a congregate setting essay at a medium-sized college setting is assumed for the analysis.

Note: A lag of 8 hours after individuals receiving a positive test result (true or false) is assumed. Those exhibiting COVID-19 symptoms would be moved from the general population to an isolation dormitory, where their infection would be confirmed and receive supportive care from which no further transmissions would occur. The lag reflected both test turnaround delays and the time required to locate and isolate identified cases.

Contacts

We encourage suggestions of new features and improvements to make the visualizations more helpful. The developers can be contacted below.

References

Paltiel AD, Zheng A, Walensky RP. Assessment of SARS-CoV-2 Screening Strategies to Permit the Safe Reopening of College Campuses in the United States. JAMA Netw Open. 2020;3(7):e2016818. doi:10.1001/jamanetworkopen.2020.16818