It was just a test -- I believe.
The death rate for the Spanish flu was only 2.5% but it killed over 20 million people. The virus may mutate as it ages and develops. At the end of the cycle with Spanish it had mutated and was killing 28% ...
The Chinese might even kill off 20% of their population with SARS ... which might be a good thing for them. They have far too many people.
But why in Hong Kong?