It is because of the consequences of covid-19 on the lungs of some people, which needs intensive care and specialized equipment to cure them, that is rare (ventilators etc.).
Also the length of time that people stay on it, with covid-19 it seems to be 2-3 week so bed and staff turnover is slow, which meant you need many more people that are available.
ICU "bed" is a virtual term, it not only means the physical availability of ventilator, but also staff.