Table 1.
Privacy characteristics of COVID-19 contact tracing and exposure notification apps.
| Country | App name (month of launch) | Voluntary or mandatory | Technology | App data bound by privacy laws | Consent for data sharing required | Centralized or decentralized data storage | Approximate adoption rate, % (month of reporting) |
| Australia | COVIDSafe (April 2020) [5] | Voluntary | Bluetooth [5] | Yes | Yes | Centralized | 21.6 (July 2020) [6] |
| China | HealthCode (February 2020) [7] | Voluntary (required to move around cities) | May use GPS or records of individual’s location | Yes | No | Information not found | ~64 (April 2020)a [8] |
| Canada | COVID Alert (July 2020) [9] | Voluntary | Bluetooth | Yes | Yes | Decentralized | ~15 (December 2020)a,b [10] |
| Germany | Corona-Warn-App (June 2020) [11] | Voluntary | Bluetooth | Yes | Yes | Centralized (pseudonymized contact identifiers) | 1.4 (July 2020) [6] |
| Hong Kong | StayHomeSafe (April 2020) [12] | Mandatory for 14-day home quarantine | Bluetooth and geofencing technology using wristbands | Yes | Yes | Decentralized | Information not found |
| Hong Kong | LeaveHomeSafe (November 2020) [12] | Voluntary | QRc codes | Yes | Yes | Decentralized | Information not found |
| New Zealand | NZ COVID Tracer App (May 2020) [13] | Voluntary | Bluetooth, QR codes, location alert through push notifications | Yes | Yes | Decentralized | 10.7 (July 2020) [6] |
| Russia | Social Monitoring (April 2020) [14] | Mandatory for individuals with COVID-19; voluntary for others | App seeks consent to access Bluetooth, GPS, and camera | Yes | Yes | Centralized | Information not found |
| Singapore | TraceTogether (March 2020) [15] | Voluntary (required to move around the city) | Bluetooth | Yes | Not for infected persons | Centralized | 70 (December 2020) [16] |
| South Korea | Self-Quarantine Safety Protection (March 2020) [17] | Required for new arrivals for 2 weeks (telephone calls are alternative option) | Bluetooth, GPS, credit card transactions, surveillance cameras, and others | Yes | Yes | Centralized | Information not found |
| South Korea | Corona 100m (February 2020) [18] | Voluntary | GPS, uses data from public government sources | Yes | No | Decentralized | ~2 (end of February 2020, 3 weeks after rollout)a [18] |
| Saudi Arabia | Tawakkalna (May 2020) [19] | Voluntary | GPS | Information not found | Information not found | Centralized | 4.9 (July 2020) [6] |
| United Kingdom | NHS COVID-19 (September 2020) [20] | Voluntary | Bluetooth 4.0 or higher | Yes | Yes | Centralized (nonidentifiable information) | 40 (October 2020) [21] |
aEstimated adoption rate based on number of downloads divided by the country’s entire population.
bIn Canada, the app was rolled out in Ontario first; as of December 2020, only 9 of the 13 provinces and territories had adopted the app.
cQR: quick response.