A meme has been established that smart phone contact tracing apps need at least 60% adoption to provide any benefit. That is not the correct interpretation as their could be detections at lower adoption levels, and if you detect anyone, then that is defined as a “benefit”, albeit, it may be a very small benefit – such as detecting one or two potential contacts, which is probably not sufficient to make any difference in disease spread.
MIT Technology Review cites Iceland as an example of 40% adoption rate and suggests this is a “significant level of adoption”.
Uhhh, no, and the source they cited to make this claim actually says the app “hasn’t helped much”.
MIT Technology Review did not, apparently, read the article – or even the headline – they cite as evidence for that conclusion. They write this claim:
Some countries have reached significant levels of adoption: Iceland has achieved around 40% usage, while others such as Qatar and Turkey have made downloading their apps mandatory.
Here is the title and sub title of the article they cite as saying 40% is a good number in Iceland:
Nearly 40% of Icelanders are using a covid app—and it hasn’t helped much
The country has the highest penetration of any automated contact tracing app in the world, but one senior figure says it “wasn’t a game changer.”
When reading news reports, regardless of the source, you must be skeptical. This is what their cited reference says about the use of the contact tracing app in Iceland:
“The technology is more or less … I wouldn’t say useless,” says Gestur Pálmason, a detective inspector with the Icelandic Police Service who is overseeing contact tracing efforts. “But it’s the integration of the two that gives you results. I would say it [Rakning] has proven useful in a few cases, but it wasn’t a game changer for us.”
Not a great endorsement.
A 40% adoption rate means it can detect potentially 20% of contacts, if using the Bluetooth method. The Iceland app, however, actually stores your GPS derived latitude and longitude and does not use Bluetooth.
Still, the 40% adoption rate means it can detect only 20% of contacts. However, by storing lat/long and time (if it does), it has the potential to detect surface contamination scenarios “across time”. No idea if it does that, however.