The United Kingdom is considering switching to a two-dose regimen for human papillomavirus immunization. A two-dose schedule for Gardasil--which is sold in Europe by a Merck ($MRK)-Sanofi ($SNY) joint venture--cleared the first European regulatory hurdle last month. If the U.K. adopts the two-shot model, it may use the cash it saves to vaccinate boys against HPV. Article