Australia’s monkeypox outbreak has grown by 21 cases in a week. 

Of 23 new locally acquired cases, 20 were announced by Victorian health authorities last weekend, followed by NSW announcing one person had caught monkeypox locally and two NSW residents had caught it interstate. There have been more than 100 likely cases since May, and Victoria now has 59 confirmed cases of the disease.

During August in Victoria, locally acquired cases jumped from about 25 per cent of all cases to 50 per cent of cases.

The state’s Deputy Chief Health Officer Deborah Friedman says case numbers will continue to rise quickly until large stocks of monkeypox vaccine can be delivered.

“We're seeing multiple cases a day now whereas previously we were seeing maybe one or two cases a week, so we've seen a substantial increase and I think it's going to continue to increase,” she said.

Dr Friedman says it is likely that many infections could not be traced.

“All of the transmission still appears to be very close and intimate contact so that's definitely still the case, but not all cases identify as gay and bisexual men,” she said.

Victoria's Health Minister Mary-Anne Thomas says has some of the vaccine for the virus, but supplies are highly limited.

“We're working hard with the Commonwealth to make sure we get vaccines rolled out here as soon as possible and we're expecting more vaccines to come in September,” she said.

Around 20,000 vaccine doses are expected to be delivered in September.

The current outbreak is disproportionately affecting men who had sex with men, but the virus can affect anyone who has prolonged close contact with another person who had the disease.

Symptoms of monkeypox can include a rash, fever, chills, muscle aches, backache, swollen lymph nodes, and exhaustion.

Meanwhile, a group of experts convened by the World Health Organization (WHO) has given new names to the monkeypox virus variants.

After a recent WHO  meeting of virologists and public health experts, it was decided that what has been known as ‘the Congo Basin variant’ will now be referred to as ‘Clade one’, and the former ‘West African variant’ will now be referred to as ‘Clade two’.

The experts also agreed that the second clade consisted of two subclades, and decided on a naming convention with a Roman numeral for the clade number and a lower-case letter for the subclades. 

This means the official names of the common variants so far are Clade I, Clade IIa and Clade IIb. Clade IIb is the group of variants dominating the current global outbreak. 

The WHO says these name changes should come into effect immediately.