A patient is still awaiting the results of tests to see if they have swine flu.
The alarm was raised on Tuesday when the unnamed patient walked into the Quayside medical practice in Newhaven showing flu-like symptoms.
They had recently been on a trip to Mexico.
The surgery in Chapel Street was immediately shut and the waiting room thoroughly cleaned as a precaution.
It reopened as normal on Wednesday.
A spokesman for East Sussex Downs and Weald Primary Care Trust said: “For protocol we rely on the Health Protection Agency. They issue the guidelines and we are standing by the advice they gave us.”
The Health Protection Agency (HPA) had previously said it would not comment on individual cases but the results of tests normally took a couple of days.
Health bosses are reminding people not to visit their GP surgery if they have flu symptoms and have recently visited one of the countries affected by the potentially fatal virus.
A free information line about swine flu, advice on viruses and preparations going on has been set up on 0800 1513513 .
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