US OFFICIALS believe a million people in the United States may already have had H1N1 flu, but because the first wave of infection has been relatively mild in the United States, those people did not seek medical care.

The relative mildness so far of the flu in the United States has also led some people to become complacent in the face of (A)H1N1. They were wrong to do so, the officials said.

'This is a serious virus capable of causing severe disease and death. It is time to be vigilant. We must avoid complacency and ensure we are prepared to deal with whatever the fall flu season brings,' said Ms Sebelius.

The United States has the highest death toll from swine flu of any country in the world, with 170 dead. In Mexico, where the outbreak began in April, 121 people have died from the illness.

Ms Sebelius said 'preparedness grants' worth US$350 million will be made available to state and local public health authorities to help them step up preparations, and urged individuals and businesses to map out their own plans for tackling H1N1 flu. -- AFP