Preventing community spread is a far more effective measure than closing borders. That is what China focussed on in the Wuhan area and the results have been excellent
You need both measures.
But closing schools, mass transit, factories affect far more people than closing the airline industry. It will need to get a lot worse before that is politically acceptable.
However we will almost certainly get there and I expect very long Easter school holidays.
this is surprising politicians also. On Thursday that Vic Premier still thought he had a car race.