It may be years before scientists can determine an optimal human dose for the new Ebola vaccine. That does not mean, however, that it won't soon enter the national stockpile. The Bush administration says that next year it expects to purchase 75 million doses of a new anthrax vaccine that has not yet even completed human safety trials.
Of course, Nabel says, "you can bet there would be follow-up studies if the Ebola vaccine was used in a real outbreak." He acknowledges, however, that "if the vaccine is so good that it aborts infection before the virus induces an immune response, we might not be able to tell who was exposed and who wasn't."