The public political answer to your question is next to zero infection rate with zero deaths as that is the only acceptable answer to many in the community. The real answer is harder to quantify but if you look at it objectively from a pure numbers point of view anything under 1% is probably acceptable. Now obviously we don't want that to happen.
IMHO the key has always been to manage this virus to ensure our health system can cope as if it doesn't then more people die unnecessarily from the virus and other causes due to the system being overwhelmed.
