An elderly man wears a surgical mask on April 28, 2009 along a street in Hong Kong - a city familiar to masks after SARS in 2003 and more recent alerts over bird flu. Authorities across the region have moved quickly to try to prevent the spread of swine flu, which is suspected of killing more than 100 people in Mexico and may have spread to Europe, the Middle East and New Zealand. Getty Images logo Getty Images 37 months ago

An elderly man wears a surgical mask on April 28, 2009 along a street in Hong Kong - a city familiar to masks after SARS in 2003 and more recent alerts over bird flu. Authorities across the region have moved quickly to try to prevent the spread of swine flu, which is suspected of killing more than 100 people in Mexico and may have spread to Europe, the Middle East and New Zealand.