this shows the timeline https://en.wikipedia.org/wiki/Timeline_of_the_2019–20_Wuhan_coronavirus_outbreak_in_February_2020
note - The first cases were actually reported in china on the 12th Dec. Up to 16th Jan (35 days later) China reported only 45 confirmed cases
If you compare this with the spread outside of China (1st case 17th Jan), despite the quarantines, travel limitations etc, the confirmed cases has grown from 1 to 452 in 22 days.
This could lead you to assume the actual infected number in china is massively higher than the confirmed cases.
The only good news is that outside of china, the deaths are still at 2 out of 452, mortality rate 0.4%.
Of the patients who are being treated in hospital, the typical severe cases require oxygen support for a few days to enable recovery.
The fear is that if the hospitals become overwhelmed with severe cases, there will be a shortage of oxygen.