Swine flu has claimed its first two South African victims - both of them women.
The two unidentified women recently visited Mexico, epicentre of the new disease sweeping the world.
Both women - one from Gauteng, the other from Western Cape - have displayed "mild symptoms" of the potentially killer disease, Lucille Blumberg, deputy director of the National Institute of Communicable Diseases, said yesterday.
She said South African laboratories could still only do preliminary tests and that the results of suspect cases were then sent overseas for confirmation.
Reagents that will allow local laboratories to complete definitive tests are expected in days, she said.
Blumberg said health authorities had established a stockpile of antiviral flu medicine but she conceded that further stocks would have to be sourced overseas through the World Health Organisation if a pandemic broke out.
If this strain of the H1N1 virus does sweep the world in a pandemic, the demand for the drugs could overwhelm manufacturers.
Most strains of flu that affect animals do not cross species, but they are particularly dangerous when they do and mutate into a form that can be passed person-to-person because humans have no natural resistance.
The body builds resistance to viruses that are in circulation, but new mutations sometimes sweep the world in pandemics that can kill millions of victims with no natural defences.
Blumberg warned that South Africa was entering its "normal flu season" and said people who had symptoms such as high temperatures and sniffles should not assume they had picked up swine flu.
"People at risk should already be vaccinated," she said.
Usually the young, the old, those with respiratory diseases and those with suppressed immune systems are most susceptible to flu.
But this flu has claimed a high toll in Mexico among young adults who would normally be most resistant.