Since this flu strain is spreading rapidly throughout the world, with Columbia being added Sunday, health officials warned a "pandemic" is still considered likely. But this so-called "Phase 6" alert could be a pandemic of mild disease.
"Level 6, which they very well could do this week, all that means is that it is widespread around the world" Secretary of Homeland Security Janet Napolitano said in an interview with CBS.
Researchers are continuing to work on a swine flu vaccine, but no one is certain how and when it would be used.
"It's being grown and tested as we speak, and ultimately, the scientists will tell us whether or not production of that vaccine makes sense," said Kathleen Sebelius, Secretary of Health and Human Services.
In Canada, officials now have the first documented case of the swine flu actually infecting swine. However, authorities are emphatic that pork is safe to eat.
"I want to be clear right now that there is no food safety concern related to this finding," said Dr. Brian Evans, Chief. Vet. Officer in Canada.
The Egyptian government, however, is not convinced. Authorities there ordered that all pigs be slaughtered, triggering clashes between police and pig farmers.
In china and Singapore, officials are reportedly asking arriving Mexicans to identify themselves, then putting them in isolation, even though they show no symptoms of the flu. As many as 70 Mexicans there are reportedly under quarantine.
Conditions in Mexico, the epicenter of this outbreak, appear to be improving. The country's health minister said Sunday that the epidemic was slowing and that it reached its peak up to a week ago.
In the United States, top health officials blitzed the Sunday talk shows with a message of cautious optimism.
"Here, we're seeing encouraging signs that this virus, so far, is not looking more severe than a strain we would see during flu season," said the Centers for Disease Control's Dr. Richard Besser.
