US president Barack Obama said today the United States was responding aggressively to the new flu strain because its spread from human to human had created the potential for a pandemic.
"Unlike the various strains of animal flu that have emerged in the past, it's a flu that is spreading from human to human. This creates the potential for a pandemic, which is why we are acting quickly and aggressively," Mr Obama said in his weekly radio address.
The swine flu strain has killed up to 101 people in Mexico and infected many more, prompting the government to shut down large parts of the country. The virus has been identified in 15 countries. The only death outside Mexico was a child from Mexico being treated in Texas.
Mr Obama summarised some of the steps his administration had taken to address the virus, including recommending schools and child care facilities close for up to two weeks in the event of a confirmed case and urging businesses to allow infected workers to take as many sick days as necessary.
He said the United States had in its strategic stockpile 50 million courses of an antiviral treatment that works against this particular strain of flu.
The federal government has delivered a quarter of that stockpile to states where it may be needed and ordered an additional 13 million courses of treatment to replenish the stockpile, Mr Obama said.
"Out of an abundance of caution, I have also asked Congress for $1.5 billion if it is needed to purchase additional antivirals, emergency equipment, and the development of a vaccine that can prevent this virus as we prepare for the next flu season in the fall," Mr Obama said.
He paid tribute to the work the Bush administration did in 2005 to prepare for a possible avian flu pandemic, saying it put the government in a better state of readiness to meet the current outbreak.
"States and the federal government have fully operable influenza readiness plans and are better prepared to deal with such a challenge than ever before," he said.
Reuters