US President Barack Obama on Saturday declared the swine flu outbreak a national emergency.
The White House said Obama signed a proclamation that would allow medical officials to bypass certain federal requirements. Officials described the move as similar to a declaration ahead of a hurricane making landfall.
Swine flu is more widespread now than it has ever been and has resulted in more than 1,000 US deaths so far.
Health authorities say almost 100 children have died from the flu, known as H1N1, and 46 states now have widespread flu activity.
The White House said Obama signed the declaration on Friday evening.