Four people in Otago and five in Southland, who were on flight NZ1 which arrived in New Zealand from Mexico on Anzac Day, are in voluntary quarantine in their homes.
[comment caption=Are you worried about swine flu?]Otago and Southland medical officer of health Dr Marion Poore said none of them had symptoms of influenza.
Home quarantine means those people stay at home and do not have visitors, to limit the potential spread of infection.
Public Health South is asking people who have returned from Mexico or North America on Flight NZ 1 on Saturday April 25 to contact Public Health South.
People who were on that flight and had influenza-like symptoms should contact their medical centre by telephone to discuss their concerns, rather than just arriving at medical centres or hospitals, Dr Poore said.
People who arrived on other flights are not considered to be at increased risk.
The national pandemic alert status was raised to "code yellow'' this morning, which is a standby phase to alert the health sector there has been significant development in the virus overseas, or isolated cases in New Zealand.
The Otago and Southland District Health Boards are setting up ``incident response centres'' to manage the code yellow alert.
"While we realise this is an unsettling time for people because of talk about a pandemic [world-wide outbreak], the health sector and other agencies have been planning for this situation for some time.
"It is important the public is aware of what is happening.''
Guidelines:
• The single most important way to protect against influenza is regular and effective hand washing.
• When coughing or sneezing also, cover your mouth and nose with a tissue. Afterwards, promptly dispose of the tissue and wash your hands.
• Keep your hands away from your mouth, nose, ears and eyes as mucous membranes can let the virus in to your body.
