Commuters wear masks as a precaution against flu while riding a bus in the western Ukrainian city of Lviv,  Wednesday, Nov. 4, 2009. Russia and Slovakia have tightened their borders with Ukraine as the World Health Organization began investigating a suspected swine flu outbreak. The European Union says it is coordinating closely with health experts in Ukraine to help it cope with a suspected swine flu outbreak. AP Photo logo AP Photo 3 weeks ago

Commuters wear masks as a precaution against flu while riding a bus in the western Ukrainian city of Lviv, Wednesday, Nov. 4, 2009. Russia and Slovakia have tightened their borders with Ukraine as the World Health Organization began investigating a suspected swine flu outbreak. The European Union says it is coordinating closely with health experts in Ukraine to help it cope with a suspected swine flu outbreak.