New evidence showing the delta variant is as contagious as chickenpox has prompted U.S. health officials to consider changing advice on how the nation fights the coronavirus. Recommending masks for everyone and requiring vaccines for doctors and other health care providers are among measures the Centers for Disease Control and Prevention is considering. That’s according to internal documents obtained by the Washington Post. The presentation for CDC staff tells them to “acknowledge the war has changed.” It also notes that infections in vaccinated people may be as transmissible as in the unvaccinated.