Remember the Spanish flu?

Of course you don't. It killed 50 million people in 1918-1919.

Now the swine flu outbreak in Mexico has some parallels:

"This is an animal strain of the H1N1 virus, and it has pandemic potential because it is infecting people," said the WHO's director-general, Margaret Chan, as public health experts gathered in emergency session in Geneva to discuss the outbreak.

The mutant vaccine-resistant strain - a previously unseen combination of pig, bird and human and viruses - is causing panic in Mexico's capital, one of the world's biggest cities where most of the victims have died.

Mexico City's mayor has cancelled all public events for 10 days and school, colleges and museums have been closed. Alarmed residents are stockpiling food to hole up at home or packing bags and leaving the city - an exodus that could spread the disease.

Most of the victims have been aged 25 to 45 and the disease is thought to have been passed from person-to-person, heightening fears that the virus could be the beginning of a pandemic. Men and women in their prime were the greatest casualties of the so-called Spanish flu that wiped out about 50 million people after the First World War.

More than 1,000 people have fallen ill in Mexico with suspected flu, while eight people in the bordering US states of California and Texas have also been infected. In New York, 75 children from a private school in Queens who fell sick with flu-like symptoms last week were being tested for the disease after it emerged that some pupils recently visited Mexico.

Miss Chan said the strain is still poorly understood and the situation is evolving quickly. "We do not yet have a complete picture of the epidemiology or the risk, including possible spread beyond the currently affected areas," she said. "Nonetheless, in the assessment of WHO, this is a serious situation."

Good news: Tamiflu works to reduce the symptoms of those infected with this new strain. Bad news: there ain't nearly enough Tamiflu to help everyone if this becomes a pandemic.

Wash your hands often. Avoid crowds. Consider a face mask if going to an area with an outbreak.