This is false and shows you don't understand how the covid vaccines work, and you don't know what happened in Australia.
I live in Australia and we suffered some of the harshest lockdowns in the world. Cases were kept low because states closed their borders, not allowing anyone in. People were locked down in their homes, not allowing anyone out.
This went on for literally hundreds of days in some parts of the country, even those places with high vaccination rates.
We had strict curfews; we had 5km travel limits enforced by cops and "ring of steel" checkpoints. It was illegal to go the beach; it was illegal to take your kids to the park; it was lawful for cops to chase and attack people for not wearing masks outside. We had overzealous state premiers granting themselves new powers. We had propaganda campaigns of fear - our government hired young actors to die slowly on ventilators... (https://youtu.be/5v0Xc4dWYH4)... when the rest of world chose constructive public health messaging, we went for "shock and awe" to scare people into not going outside.
Yet, here you are claiming we had "herd immunity"! Do you realise that not everyone takes the vaccine at the same time, and that only a small proportion of vaccinated people at any given time have the full protection offered before the vaccine fades? That window of time being as little as 4 months? Herd immunity was never more than wishful thinking.