Alberta TraceTogether (Herald Protocol) Results 2021-03-22


A formal test was carried out for Alberta TraceTogether v2.0 just prior to release. With the agreement of Alberta Health the Herald project are publishing the results here.

The test consisted of ten phones. One phone (iPhone7+) failed during the test and has been discounted from the results. The likelihood is that the true results are, therefore, better than quoted here.

It should be noted that the results on this page are tuned for mobile phone use in Canada whereas all other standard Herald tests are for the UK.


Measure Result Notes
Traceable Interaction Fraction 83.77% Used as input to OpenABM simulation
Overall Efficacy 47.00% Effective
(Canada MAX 55.20%)
Probability of detection 87.95% Formal RISK detection
Phone Detection 100% Includes iOS in the background
Continuity 93.19% Full continuity
Completeness RT1 98.36%
Completeness RT2 TBD Not yet calculated from data
Completeness CE 95.95%
Accuracy 95.95% RSSI accuracy
Longevity 100% 8 hour test
Mean time
between readings
Country Canada
Have BLE Phones 83.75% Statista
Hardware Support 99.18%
Software/OS Support 98.40%
Overall Pspec 81.73%
Pspec squared 66.8%

Phones tested

PhoneId Phone Make and Model OS and version Known issues
1 Pixel 3XL Android 19
2 Samsung A10 (SM-A105FN) Android 28 A10s knowingly rotate their BLE MAC address with every request. Herald uses an ephemeral ID that rotates every 15 minutes as a performance improvement.
3 Samsung A40 (SM-A405FN) Android 29 Same issue as A10 above
4 Samsung A70 (SM-A705FN) Android 29
5 Samsung S10-lite (SM-G770F) Android 29
6 iPhone 6 iOS 12.4.2
7 iPhone 7 iOS 13.6 Phone’s name is Adam’s work iPhone
8 iPhone SE 1st gen iOS 13.6
9 iPhone X iOS 13.7

Fair Efficacy Stats Summary

Phones Max Pairs Pairs Detected Detection Percent Max 30 second windows 30 second windows achieved Missed windows percentage Longevity change over 8 hours
9 72 72 100% 70560 65751 6.815476% 0.00%

OpenABM Simulation

The below shows the effect on COVID-19 spread of 100% adoption of the application under test, and 80% conformance to self-isolation advice. Note: The simulation still shows a control effect on COVID-19 spread with lower app uptake.

Initial seed data:-

  • Alberta population as of 1st Jan 2021 of 4,436,258 - Source:
  • Alberta current (Day 1) COVID-19 live cases on 18 Mar 2021 of 5,342 - Source:
  • No other sources of control (lockdown, masks, etc.)
  • 200 day simulation

OpenABM Simulation results - cases

Phone detection and distance estimation reports

The below 9 charts show discoveries, ID (data payload) reads, and RSSI (distance estimation) readings as individual dots.

A10 results A40 results A70 results S10-lite results iPhone 6 results iPhone 7 results iPhone SE 1st genresults iPhone Xresults

The below charts show RSSI variation over time. In a formal test these will mostly be static.

A10 RSSI A40 RSSI A70 RSSI S10-lite RSSI iPhone 6 RSSI iPhone 7 RSSI iPhone SE 1st gen RSSI iPhone X RSSI

Getting Started

To help you get started, see the documentation.