Why does the health ministry keep just saying this? How have they not already built more capacity? Why just wait for it to happen?
This bothers me too, but one answer might be that it takes time to train more doctors and nurses - you may be able to quickly convert any building to hospital beds, but you need to staff it.
The only way to get more staff quickly is to transfer from other duties - nurses in kupot cholim, psyc wards, schools - but even this is limited (have you ever been to a mirpa: nurses are only there till 9 or 10 am) and would still require some sort of retraining - plus I would guess that Israeli union rules would make it difficult to do anyway.