Table 2.
Metrics to evaluate ideal DCTA effectiveness.
| Indicator of effectiveness | Purpose | Metric numerator (source) | Metric denominator (source) |
| DCTAa is downloaded | To estimate the proportion of the smartphone owning population who download the DCTA | Number of DCTA downloads minus number of DCTA deletions (DCTA) | Number of smartphone owners nationally (Government statistics office; eg, Central Statistics Office, ROIb) |
| DCTA is active | To estimate the proportion of DCTAs downloaded that are being used | Number of DCTAs with contact tracing turned on (DCTA) | Number of DCTAs downloaded minus number of DCTAs deleted (DCTA) |
| DCTA is active | To estimate the proportion of DCTAs downloaded that are being used | Frequency and duration of use (DCTA) | N/Ac |
| DCTA is active | To estimate the proportion of DCTAs downloaded that are being used | Number of DCTAs downloading TCNsd of cases on central server per day (assuming DCTA downloads keys once per day when active; DCTA) | Number of DCTAs downloaded minus number of DCTAs deleted (DCTA) |
| DCTA is used by COVID-19 cases | To estimate the DCTA penetration among people who contract COVID-19 | Number of positive test results uploaded to DCTA (DCTA) | Number of COVID-19 cases nationally (national surveillance data) |
| DCTA is used by COVID-19 cases | To estimate the DCTA penetration among people who contract COVID-19 | Number of COVID-19 cases who attended a screening center reporting DCTA active use (survey of attendees at testing centers and review of participants’ test results) | Number of COVID-19 cases who attended a screening center (screening center data) |
| DCTA is used by COVID-19 cases to notify close contacts | To estimate the proportion of cases using the DCTA who use it to send contact alerts | Number of DCTAs that send a contact alert (DCTA) | Number of DCTAs with a positive COVID-19 test recorded (national surveillance data) |
| DCTA is used by COVID-19 cases to notify close contacts | To estimate the proportion of cases using the DCTA who use it to send contact alerts | Number of COVID-19 cases who attended a screening center reporting DCTA active use and who report sending a contact alert (follow-up survey of COVID-19 cases who reported DCTA use at time of screening) | Number of COVID-19 cases who attended a screening center reporting DCTA active use (survey of attendees at testing centers and review of participants’ test results) |
| Close contacts using DCTA receive alert | To estimate the DCTA penetration among people who are close contacts | Number of DCTAs that receive a contact alert (DCTA) | Number of close contacts identified nationally (national surveillance data) |
| DCTA identifies contacts not identified by manual contact tracing | To demonstrate the DCTA augments manual contact tracing | Number of close contacts attending testing center identified exclusively by DCTA (survey of attendees at testing centers) | Number of close contacts attending testing center (survey of attendees at testing centers) |
| DCTA identifies contacts sooner than manual contact tracing | To demonstrate the DCTA augments manual contact tracing | Number of close contacts attending testing center who received contact alert from DCTA before contact alert from manual contact tracing service (survey of attendees at testing centers) | Number of close contacts attending testing center (survey of attendees at testing centers) |
| Close contacts using DCTA are tested for COVID-19 | To estimate the proportion of contacts who are tested for COVID-19 and to estimate the number of cases identified by the DCTA | Number of DCTAs with a COVID-19 test result uploaded within 14 days of a contact alert (DCTA) | Number of DCTAs that receive a contact alert (DCTA) |
| DCTA associated harm is recognized | To determine what harms, if any, occur with DCTA use | N/A (qualitative survey of DCTA users) | N/A |
aDCTA: digital contact tracing app.
bROI: Republic of Ireland.
cN/A: not applicable.
dTCN: temporary contact number.