Data on the way the swine flu virus behaves in New Zealand and other parts of the southern hemisphere will help a World Health Organisation (WHO) taskforce decide whether it warrants a vaccine, and how that should be used.
Researchers around the world are doing preliminary work for production ofa vaccine, amid concerns that the virus may mutate and acquire greater virulence by mixing with seasonal flu viruses during the southern hemisphere winter.
Swine flu is a type A H1N1 influenza - as are some seasonal flu viruses - but contains sufficient genes from birds and North American and European pigs to not trigger a useful immune response in humans.
Seasonal flu strains constantly evolve, but are often recognised by human immune systems, especially if people have kick-started that response with a vaccination.
Normally the WHO makes twice-yearly recommendations to guide the formulation of vaccines covering three types of seasonal flu: one recommendation in February for the northern hemisphere winter and another in September for the next southern hemisphere winter.
But a WHO taskforce in Geneva is discussing what to do with any swine flu vaccine which is produced, New Zealand National Influenza Centre head Dr Sue Huang said.
"The global vaccine (production) capacity is limited - if you do the swine flu vaccine, it means you have to sacrifice some of the seasonal vaccine capacity," she said.
"This is a very big issue."
Dr Huang noted that monitoring of the virus in the southern hemisphere was "very very important" as it entered its flu season.
The monitoring ESR was mounting in New Zealand for swine flu virus would contribute to the international response, she said.
New Zealand and South African representatives are expected to meet the Australian Influenza Vaccine Committee (AIVC), in October to consider whatever WHO recommends as a southern hemisphere seasonal influenza vaccine composition for 2010.
