Australia's Deputy Chief Medical Officer says the country is "probably on the cusp" of forcing the coronavirus infection rate down to a point where the virus could die out, as case numbers continue to slow in Victoria.

The daily growth rate as a percentage of total cases has fallen from about 20 per cent in late March, to an average of 1.8 per cent over the past week. On Friday, a growth rate of 1 per cent was recorded.

Professor Paul Kelly struck a positive tone. Credit:Alex Ellinghausen

Deputy Chief Medical Officer Paul Kelly said the overseas infection rate for COVID-19 was "disturbing", with international results showing infected people can pass it on to as many as five others. But he said Australia's successful social distancing measures were helping drive the rate closer to a further one or two infections per person.

"Ideally, where you want to be is below one. So less than one other person being infected, after a person themselves had the infection," he told reporters in Canberra.