Profesor Lindsay Davies, national director of pandemic influenza preparedness for the Department of Health, said swine flu hot spots had emerged near private schools.
She was speaking at the British Medical Association annual conference of public health medicine.
"Many of the people bringing it back (swine flu) were well off people who had been to fancy places on holiday," said Prof Davies
"Many hot spots included public schools."
Those most affected by the outbreak were children, she said, leading to many school closures, including a number of public schools.
And Prof Davies claimed the virus could be around for a long time, with five people currently in intensive care in London and a further 25 in London hospitals.
In Britain, 457 have died since the H1N1 virus broke out almost a year ago.
Several million Britons have had swine flu, many of whom will either have had no symptoms or a mild illness.
