Melbourne: CSL Ltd., the only flu-vaccine maker in the Southern Hemisphere, will send trial material to the US this week to test an inoculation against swine flu, Rachel David, a spokeswoman for the Melbourne-based company, said on Tuesday.

CSL will stockpile bulk antigen for use in pandemic flu vaccine until the material is requested by the US Department of Health and Human Services, David said.

Meanwhile, US is readying its first human trials for the experimental vaccine to protect against the H1N1 swine flu virus, officials announced Wednesday.

Two possible vaccines will be tested at eight institutions around the country under the auspices of the National Institute of Allergy and Infectious Diseases (NIAID)

On Tuesday it was revealed that two Australian biotechnology companies have started inoculating adult volunteers in the world's first H1N1 swine flu vaccine trials.

Those trials, as well as the trials planned in the US, hope to produce an effective shot against the virus that has so far killed more than 700 people worldwide.

In the United States, several trials will be conducted concurrently, officials said.