The United States, Mexico and Canada on Monday vowed new vigilance against an expected resurgence of swine flu in coming months, in a joint summit communique.
"We will remain vigilant and pledge to continue our close collaboration in addressing the H1N1 pandemic," US President Barack Obama, Mexican President Felipe Calderon and Canadian Prime Minister Stephen Harper said in western Mexico.
"In anticipation of a possible fall wave of flu due to the 2009 H1N1 virus, we will look to enhance our exchange of information, ensure common understanding of the effectiveness of public health measures, and share expertise," the three leaders said in a declaration.
They added that measures such as general border closures would be unlikely to prevent the spread of the virus, and could aggravate the economic and social consequences of a pandemic.
"We know that H1N1 will return in winter," said Calderon, as Mexico prepared a new public information campaign for October, and after the death toll has crept up in the country's impoverished southeast in recent weeks.
"We three countries are preparing to confront this virus responsibly and minimize its impact for our people," Calderon said.
Most of the world's swine flu deaths -- 1,008 -- have occurred in the WHO's America's region, encompassing North and South America and including Mexico and the United States, the countries where the virus first appeared.