An unprecedented outbreak of measles in New Zealand is spilling over into Australia, infectious diseases specialists warn.

Australia needs to double-down on efforts to control transmission, particularly in hospital EDs and clinic waiting rooms, the doctors told a briefing for journalists ahead of the launch of a new public awareness campaign.

There have already been more cases in the first six months of this year than in all of 2018, they say.

Infectious diseases physician Professor Allen Cheng, from the Alfred Hospital in Melbourne, said that up to Thursday there had been 177 measles cases notified Australia-wide, compared with 103 cases in 2018.