The outbreak of swine flu that has killed at least 81 people in Mexico has raised a lot of questions, said Donald G. McNeil Jr. in The New York Times. Is the large number of deaths among healthy adults in Mexico a sign of a coming killer pandemic? Or, since the 20 cases in the U.S. were all mild, will most of those infected survive?  "Right now, the answer is unknowable."

One of the most troubling questions, said Japan's Daily Yomiuri in an editorial, is whether this strain of swine flu has mutated to permit human-to-human transmission. If it has, we could be in for a pandemic of a new type of flu many nations have feared for years. To really know what we're up against, "international cooperation is urgently needed."

So far, the cooperation among global health authorities has been a bright spot, said Tom Bemis in Marketwatch. They've been sharing information "quickly, and one hopes accurately." It looks like everyone knows how many lives could be at stake, and how badly the global economy would suffer from the "quarantines" and international barriers a pandemic would bring.