20% needing hospitalisation is a known figure based on existing cases.
3.5% is the known case fatality rate.
these figures are not opinions, they come from the WHO and other medical sources.
From Business Insider:
“South Korea has tested more than 140,000 people for the new coronavirus and confirmed more than 6,000 cases. Its fatality rate is around 0.6%.
This suggests that, as many health experts have predicted, the virus' fatality rate seems to decrease as more cases are reported.
That's because more widespread testing leads more mild cases to be included in the count.
The US, by contrast, has tested around 1,500 people. The country has 221 confirmed cases and 12 deaths, suggesting a death rate of 5%.
The US' testing capacity has been limited.
The US and South Korea announced their first cases of the coronavirus on the same day: January 20. More than six weeks later, the US Centers for Disease Control and Prevention has tested around 1,500 people for the virus. South Korea, meanwhile, has tested about 140,000.
The nation is capable of conducting as many as 10,000 tests per day and has built drive-thru testing clinics that can detect coronavirus cases in just 10 minutes. Officials say the clinics can reduce testing time by a third.
This quick response has allowed South Korea to detect more than 6,000 coronavirus patients, around 35 of whom have died. That means the country's fatality rate - the number of deaths out of the total number of infections - is around 0.6%.
The World Health Organization estimated on Tuesday that the global fatality rate for the coronavirus is around 3.4%. Some health experts predict that this rate will decrease as the number of cases rises. South Korea offers solid evidence for that prediction so far.”
