A security guard wearing a surgical mask gives anti-bacterial soap to a visiting woman in the National Museum of Anthropology and History after it was reopened, in Mexico City May 7, 2009. Millions of high school and university students returned to classes in Mexico as the government said the worst of the flu crisis is over and the country got back on its feet after shutting public places last week to avoid spread of the virus. REUTERS/Eliana Aponte (MEXICO EDUCATION HEALTH ENVIRONMENT)