The main natural disaster that effects Victoria are bushfires, floods and wind. It is not cyclone prone, for example, and whilst it does get occassional tremors, not particularly earthquake prone either.
The first two are manageable through finding a suitable location out of fire and flood risk areas (and probably best not to co-locate with other vaccine production) and third and earthquakes through design of the structures. I'm struggling to think of two pieces of non co-located infrastructure in Victoria that have been affected by natural disasters at the same time - or even by the much more likely industrial accidents/human caused disasters. The last significant piece of infrastructure in the state that was "taken" out - and my memory may be a bit faulty - that I can recall was the Longford Gas Plan in 1998.
On the positive side, the support that is provided by an expertise retain in Melbourne & Monash Universities and the Doherty Institute probably is a huge plus for a Victorian location.