Australia's swine flu alert has been raised to containment level after confirmation of the first victims who had not travelled overseas recently.
Health authorities are concerned that neither a 17-year-old Victorian boy nor a 15-year-old South Australian girl with the H1N1 virus has travelled recently or been in contact with anyone carrying the disease.
The girl recently returned from a camping trip to Mildura.
The boy lives in the same area as Melbourne's Clifton Hill Primary School, which has been closed after two brothers, aged nine and 10, who holidayed in the United States, became sick and infected a fellow classmate.
Australia's chief medical officer Professor Jim Bishop said on Friday those cases and the first known cases of human to human transmission were a "worry".
There are now 12 cases of the virus in Australia.
Professor Bishop said it was still a small number, but that it would rise. The priority now was containing how many people were infected with swine flu.
The contain phase means the government is ready to distribute as many of the 8.7 million cases of Tamiflu and Relenza medicine it needs, Federal Health Minister Nicola Roxon said.
Of the 12 cases confirmed, seven are in Victoria, two in New South Wales, two in South Australia and one in Queensland. Another 28 people have been tested and are awaiting results.
Mexico City lifts flu restrictions
All swine flu restrictions have now been lifted in Mexico City. According to latest health ministry figures issued on Thursday, swine flu has killed 78 in Mexico and infected 3930 people.
The alert system for the capital is at its lowest level, signalling that schools, businesses and transport could function as normal, without extra health precautions.
According to the World Health Organisation, the virus has spread to 41 countries, infecting more than 11,000 people and leading to 85 deaths.