In Mexico, the cloth patches in green, blue and white are everywhere, clamped tight over the mouth and nose of teachers, toddlers, policemen and drunks. But do they work? While Mexico has handed out millions of facial coverings, US officials have held off, saying there is little evidence of their effectiveness. Some doctors warn they might even be harmful, causing people to take risks — like venturing into crowds or neglecting to wash hands — in the mistaken belief that the mask protects them. Soldiers hand them out at subway stations. Pharmacies and hardware stores can't keep them in stock. Newspapers have begun running front page instructions on making do-it-yourself mouth coverings. “They must be worn when one is out in public or in a closed, crowded space,” Health Secretary Jose Angel Cordova insisted Monday, while acknowledging in the same breath that the government-distributed masks are too porous to eliminate all risk. “They still offer enough protection as a public health measure,” he offered. US health officials give very different guidance. The Centers for Disease Control and Prevention said there is not a lot of evidence that masks do much good, and have pointedly not recommended their use by the general public. Swine flu is thought to be transmitted in much the same way as seasonal flu, by touching something with the virus and then passing it to the nose or mouth or through coughing or sneezing. Experts say people who come in close contact with known swine flu patients should wear high filtration masks like those used by health professionals, which are more effective but also more expensive (about 12 pesos or a dollar) and generally unavailable in Mexico City. In the streets of Mexico's capital, almost everybody was taking the threat seriously.
