[Retric]

Diamond Princess had a slightly older population but healthy population, tested everyone, provided good medical care. They still hit 14 deaths out of 712 infected or ~2% and only had 20% asymptotic cases. South Korea has very good testing, a younger than US population, similar rates of hospitalization to DP and a slightly worse mortality rate likely due to missing some people but having a more at risk population.

The US has an older and sicker population than SK, and in NYC an overworked healthcare system. So, a 1% US mortality rate discounted to 0.5% due to recent infections not having time to die is extremely optimistic. It would also mean testing was only discovering 10% of cases.

PS: Many more people are exposed without having sufficient infections to trigger long term immunity. But, it’s herd immunity or deaths/long term issues we care about making such cases irrelevant as their still at risk.