On Wed, 16 Sep 2020 10:09:38 +0200, Carlos E.R. wrote:

What if a symptomatic person never goes to the hospital or never gets
tested? Because here there hare thousand of those.

Carlos,

I know this stuff well as I was trained in this for many years.

The apps catch a very small percentage of cases, something like 1%
in some scenarios, which is 1 out of 100 infected people,
when you factor in all the math involved, even in the best situations.

You may as well carry a talisman, as that might work even better.

The apps can't work for a variety of reasons, enumerating some as...
1. Uptake will never be anywhere near what epidemiologists claim is needed.
2. They miss aerosol, contact surface, & asymptomatic transmission.

You may as well carry around a rosary & pray a certain prayer three times.
--
The problem here is people are expecting a placebo to be effective.