There are a number of tracing apps to signal a potential exposure to Covid-19, that is if you have been in contact with an infected person. In Italy we have Immuni. It has been downloaded by 12 + million people, 19,858 of them have become infected and notified the central monitoring system, generating over 100,000 “pings” (notification to potential exposures).
In the UK people are using the NHS Covid-19 app (watch the clip). It has been downloaded by close to 27 million people and people have used the app to check info over 237 million times. It has sent close to 4 million potential exposures alerts, with the number increasing every week. In the week of July 7th 520,194 alerts have been sent.
What we are seeing is that the alert notifications are growing faster than the epidemic (that is not surprising, of course, since every infected person has proximity contacts with many people, introducing a multiplying factor).
Along with the epidemic we are now facing a “pingdemic” whose economic impact is starting to become huge. When you receive a “ping” (see the picture) you are supposed to self-isolate (initiate a quarantine), wait for a few days and then have a test to exclude infection. With an R0 in the range of 2 to 3 (that is the estimated infection rate of Covid-19) an infected person has the probability to infect 2 to 3 other persons. However, that person on average in the period of latent infectivity (when infections can be passed on to other people without the person being aware) may become in contact with 100+ persons. So only 2-3 out of 100 (these are average numbers, I am using them to make the point) would actually become infected (the real number of infections is actually lower, on average, because of various precautions in place – masks, washing hands…).
Here lies the “pingdemic” problem. If the apps were able to trace all contacts (they are not!) wee would have that for every infected person over a hundred will receive a warning and a request to self-isolate for ten days or to take a test after four and, provided it turns out negative go back to normal life.
The 500,000 that have received the ping in the UK in the week of July 7th reesulted a minimum of 2 million workday loss! You can easily see the problem. Seeing a solution to it is much more complex…