Authorities say while the presence of mosquitoes carrying the virus were detected at Sydney Airport, it was unlikely local transmission could occur given the lack of large numbers of the Aedes Aegypti mosquito.
The diagnoses come a day after the World Health Organization (WHO) declared Zika to be an international health emergency, linked to babies being born with underdeveloped brains.
WHO expert, Dr Anthony Costello, says the agency is preparing guidelines to hopefully help combat the outbreak.
"The first thing that needs to go out is to advise women, particularly women who are pregnant or at risk of pregnancy, to take every possible measure for personal protection against being bitten by mosquitoes. We need to give them the risk information. We need mass community engagement here, mobilisation of women's groups, antenatal groups and of partners who are going to do a lot to control the vector."
NSW Health Minister Jillian Skinner has moved to calm fears about the Zika virus after the infection was detected in two residents.
NSW residents shouldn't be concerned about a Zika virus outbreak in their state, the health minister says.
The infection was detected in two residents who recently returned to Sydney from the Caribbean, but Health Minister Jillian Skinner has told people not to panic.
"My advice is that there's very little likelihood of infection here. It is generally spread to mosquitoes that are exclusive to fairly tropical zones," she told reporters in Sydney on Wednesday.
