U.S. authorities say the spreading H1N1 swine flu virus appears to be much weaker than the 1918 flu pandemic virus that killed tens of millions of people worldwide.
The head of the flu division at the U.S. Centers for Disease Control and Prevention, Nancy Cox, said Friday scientists do not see the same genes in the new flu. The H1N1 swine flu is confirmed so far to have killed 15 people in Mexico and one in the United States.
Authorities in Mexico now say the H1N1 strain seems to be easily treated with anti-viral medicine if treatment is given quickly. Mexico is in the midst of a five-day shutdown in a bid to contain the illness, even as more cases are reported elsewhere.
On Saturday, South Korea reported a 51-year-old woman who had just returned from Mexico as its first confirmed case. France, Denmark and Hong Kong confirmed their own first cases on Friday.
U.S. President Barack Obama said he is optimistic the virus will be managed effectively, but that work remains to be done. Several U.S. airlines have reduced flights to Mexico because of fears over the new flu.
The flu has not reached pandemic proportions, but the Geneva-based World Health Organization is asking all countries to combat the spreading virus with "increased urgency." WHO says the virus also has been confirmed in Austria, Britain, Canada, Germany, Israel, New Zealand, Netherlands, Spain and Switzerland.
Authorities are also warning the public about a rise in flu-related scams, such as emails for unapproved treatments and masks.