A homeless youth wears a surgical mask after a routine check up for flu symptoms at a mobile clinic in downtown Mexico City May 3, 2009. Mexico has moved past the peak of an H1N1 flu epidemic and is in the "phase of descent," the government said on Sunday, although world health officials still say the unpredictable virus could become a pandemic. New cases of the virus, which mixes swine, avian and human flu strains, were still being tracked across the world.
REUTERS/Daniel Aguilar (MEXICO HEALTH SOCIETY)