LONDON, ENGLAND - JULY 30: A woman wearing a surgical mask to prevent the transmission of airborne infection walks in Westminster on July 30, 2009 in London, England. Figures released by the Health Protection Agency show that by July 19, an estimated 100,000 Britons have been infected with swine flu and there have been 26 deaths in England linked to the disease. Over 700 people worldwide have died after contracting swine flu which is spreading faster than any other flu pandemic. (Photo by Oli Scarff/Getty Images)