Table 2.
Properties of model-based studies
| Study | Model-related properties | Contact- and tracing app related properties | Disease-related properties | Modifyable properties | ||||||||
| Model type | Input parameter properties | Tracing direction | Sequential generations (n) | Adoption rate app (%) | R | Incubation time | Infectious period | Probability of disease transmission | Delay symptom onset and testing | Delay testing and feedback app | Quarantine effectiveness | |
| Bradshaw 2020 (peer-reviewed) | Branching-process model | Distributions | Bidirectional | Infinite generations | 53; 80 | 2.5 | 5.5 days | Fitted to curve, value not specified | Fitted to curve, value not specified | 1 days | 0 days | 90% |
| Bulchandani 2020 (preprint)7 | Branching-process model | Based on exponential distributions | Bidirectional | 3-infinite generations | 0–100 | 3.0 | N/A* | N/A | N/R | N/A† | 0 days | 100% |
| Cencetti 2020 (preprint)8 | Continuous weighted temporal network | Distributions | Forward | 1 generation | 60; 80; 100 | 1.2; 1.5; 2.0 | Fitted to curve, value not specified | Fitted to curve, value not specified | Fitted to curve, value not specified | 2 days | 0 days | 0%–100% |
| Currie 2020 (peer-reviewed)17 | ODE compartmental model | Based on exponential distributions | Forward | 1 generation | 0; 27; 40; 61; 80 | 2.5 | 2.0 days | 11 days | N/R | 3 days | N/R | 90% |
| Ferrari 2020 (peer-reviewed) | ODE compartmental model | Based on exponential distributions | Forward | 1 generation | 0; 25; 50; 75 | 1.5 | 5.1 days | 10 days | 10% | 2 days | N/R | 90% |
| Ferretti 2020 (peer-reviewed)16 | PDE compartmental model | Distributions | Forward | 1 generation | 0–100 | 2.0 | 5.5 days | 12 days | Fitted to curve, value not specified | 1.6 days | 0 days | 0%–100% |
| Grimm 2020 (preprint)9 | ODE compartmental model | Based on exponential distributions | Forward | 1 generation | 20–80 | 2.2; 3.0 | 5.0 days | 10;12.5;14;20 days | N/R | N/R | N/R | 100%‡ |
| Guttal 2020 (preprint)10 | Individual-based network model | Based on exponential distributions | Bidirectional | >1 generation | 100 | 3.0; 4.0 | N/A | 20 days | 0.2% | N/R | N/R | 100% |
| Kretzschmar 2020 (peer-reviewed)15 | Branching-process model | Distributions | Forward | 1 generation | 20; 40; 60; 80; 100 | 2.5 | 6.4 days | 10 days | 2%–12% | 0 days | 0 days | 0%; 20%; 40%; 60%; 80%; 100% |
| Kucharski 2020 (peer-reviewed)14 | Individual-based network model | Distributions | Forward | 1 generation | 53 | 2.6 | 5.0 days | 5 days | 20% within HH 6% outside HH 50% less for asymptomatic |
0 days | 0 days | 90% |
| Kurita 2020 (peer-reviewed) | ODE compartmental model | Based on exponential distributions | N/R | 1 generation | 0; 10; 20; 30; 40; 50; 60; 70; 80; 90; 100 |
1.5 | 6.6 days | N/R | N/R | 2 days | 0 days | N/R |
| Nuzzo 2020 (peer-reviewed)20 | ODE compartmental model | Based on exponential distributions | N/A§ | N/A§ | 0; 10; 20; 30; 40; 50; 60; 70; 80; 90 |
3.02 | 5.1 days | N/R | Fitted to curve, value not specified | N/R | N/R | 100% |
| Pollmann 2020 (preprint)12 | ODE compartmental model | Based on exponential distributions and distributions | Bidirectional | >1 generation | 60; 75; 90; 100 | 2.0–3.0–4.0 | 4.0; 7.4 days | 10 days | 7%¶ | 0; 2; 4; 6 days | N/R | 100% |
| Scott 2020 (peer-reviewed) | Agent-based model | Distributions | Forward | 1 generation | 0–50 | Fitted to curve, value not specified | 4.6 days | 8–14 days | Fitted to curve, value not specified | 1 day | 1 day | 0% in HH 80%–100% in other settings |
| Shamil 2020 (preprint)11 | Agent-based model | Distributions | Forward | 1 generation | 60; 75 | Fitted to curve, value not specified | 6.0 days | 10 days | N/R | 0 days | 0 days | 100% |
Model-specific characteristics of model-based studies looking at effectiveness of contact and tracing apps for SARS-CoV-2. Dashes (–) indicate a continuous range between numbers, semicolons indicate separate distinct values.
*Fraction of infections before symptoms are relevant.
†Isolation based on positive notification, not a positive test.
‡Changing app coverage covers imperfect isolation.
§No true tracing, fixed proportion cases will self-isolate.
¶Time-dependent, maximum value reported in table.
HH, household; N/A, not applicable; N/R, not reported; ODE, ordinary differential equations; PDE, partial differential equations; R, reproduction number.