A patient at a Clapham surgery is being tested for swine flu - also known as the H1N1 virus - but is unlikely to have the illness.
The patient went to the Clapham Family Practice (CFP) earlier this week with symptoms but had not been to the infected area.
Jim Stock, head of practice at the CFP on Clapham High Street, said the woman was being tested as a precaution.
He said: "The patient hasn't been to any of the infected areas, the likelihood is it will be negative."
There had been fears that a drug to fight the virus, Tamiflu, was in short supply in Clapham but Mr Stock said the drug would not be dispensed from chemists.
"Its life-span is so short it is not stocked locally," he said.
"It is sent by courier directly to people's houses."
• For information on health services, see our Local Information section
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