Because of demographics. The disease really, really doesn't affect young people. The younger, the better you do, to the extent that the percent of people under 20 that have died in every major area of the world rounds to 0%. Older demographics are hit hundreds of times harder than young to middle aged folks.

Italy has the oldest average population in Europe, and Lombardy has the oldest average population in Italy. 99.2% of those who died in Italy averaged 80.5 years old and had an average of 3 co-morbid conditions. [1]

[1] https://www.bloomberg.com/news/articles/2020-03-18/99-of-tho...

Italy also appears to have suffered from tragic public health errors. Apparently they moved covid-19 infected patients around. First to other hospitals that had not yet had outbreaks and then into empty beds at long-term care facilities.

https://www.cbc.ca/news/covid-19/italy-covid-19-outbreak-les...

It affects young people, it just doesn't kill them. They spread it as well as anyone else.

"spread" isn't "affected" -- someone with no symptoms who spreads it really isn't affected. The people who get it from them may well be.

So far the data is clear: it doesn't really do much to young people. [1] Speaking broadly, almost nobody under 20 has died, practically nobody under 30 has died, and a handful of 30-40 year olds have died. The trendline is super clear: if you're young, you're gonna be just fine. The CDC says young folks aren't even likely to wind up with serious disease or in the ICU ("no ICU admissions or deaths were reported among persons aged ≤19 years. Similar to reports from other countries, this finding suggests that the risk for serious disease and death from COVID-19 is higher in older age groups.") [2]

When I say "affected" I mean that they are not likely to develop serious symptoms, certainly severe symptoms and they're definitely not likely to develop life-threatening symptoms.

[1] https://www.cebm.net/covid-19/global-covid-19-case-fatality-...

[2] https://www.cdc.gov/mmwr/volumes/69/wr/mm6912e2.htm