In a development health experts are calling alarming, two bird flu patients in Vietnam died after developing resistance to Tamiflu, the key drug that governments are stockpiling in case of a large-scale outbreak. The experts said the deaths were disturbing because the two girls had received early and aggressive treatment with Tamiflu and had gotten the recommended doses. Since 2003, avian flu has killed about 70 people, mostly in Vietnam and Thailand, and nearly all involved close contact with infected birds. Health experts fear the virus could morph into a form that spreads easily between people. The new report involved eight Vietnamese bird flu patients given Tamiflu upon being hospitalized in 2004 or 2005. Half of the patients died. Lab tests showed two of those who died...had developed resistance.