This editorial appeared in The (Tacoma) News Tribune.

Faced with a potentially lethal strain of influenza, the danger lies in under-reacting.

Or overreacting – as when stock markets tremble in response to the World Health Organization's "be ready just in case" warning about swine flu.

This flu is still in the wait-and-see stage. It has killed scores of people in Mexico, the epicenter of the outbreak, but so far no Americans infected there appear to have died from the illness. No one has been able to explain the discrepancy.

The WHO's pandemic alert is at four on a scale of one to five. A four means "The new virus can cause sustained outbreaks and is adapting itself to human spread."

As far as Americans go, the right response seems to be: Don't push the panic button, but keep an eye on this thing. Stay out of Mexico, if possible.

The U.S. Department of Homeland Security's declaration of a "public health emergency" on Sunday was a primarily a move that lets the federal government begin to release disease-fighting supplies to states.

If the swine flu does catch fire in the United States, we'll have reason to thank the avian flu outbreak of 2005. That scare – combined with the SARS scare two years earlier – raised the specter of the devastating 1918 Spanish flu pandemic, which claimed perhaps 40 million lives worldwide.

To read the complete editorial, visit The (Tacoma) News Tribune.