People hear this statement and think it means that anyone that is exposed and catches the virus is able to infect anyone else, just the same as if they were completely symptomatic. But it doesn't mean it is as likely. People with symptoms are more contagious, people without symptoms are less contagious. One simple reason why is that people without symptoms tend to cough and sneeze less.

IIRC there was a study done showing symptomatic and asymptomatic carriers had the same virus load. So while you simple reason is correct, there's not much else if I understand things correctly (please correct if wrong.)

I would be interested to see that study. My understanding is that the WHO, CDC, & EU all say that asymptomatic shedding theoretically possible but highly unlikely?

Here you go https://www.thelancet.com/journals/laninf/article/PIIS1473-3...

True! But one of the major means of transportation for that virus is by coughing, which people do rarely if they are asymptomatic. Sharing drinks or other means of liquid transmission still occur, but coughing is the big one as it takes infected throat and lung fluids, and flings them all over everything. Same reason doctors really push using tissues for sneazing if you have a cold.

Touching a virus doesn't guarantee you being infected. It can't penetrate skin. Inhaling a droplet of saliva that somebody coughed up is much worse.

> I thought with this virus you can be be infected but not show symptoms for many days?

The tool takes this into account and lets you adjust the mean time before symptoms show (and the proportion who carry the virus without any symptoms).

According to the BAG (Swiss Bundesamt für Gesundheit), people are most infectious when they are experiencing the most symptoms (Fever etc.). People without symptoms are also not coughing/sneezing around which reduces the likelihood of spreading it which is probably significant enough to make a difference.

It's a numbers game. A tool doesn't have to catch everyone for it to help.