Deaths are not inevitable with any vaccine or experimental drug.

To sorta flip this comment around a bit… with any medication/vaccine/treatment, in order to demonstrate efficacy, some trial participants must specifically NOT receive the treatment. In the case of truly useful treatments, there most certainly will be people who did not receive the experimental treatment who might have benefited. We do willingly sacrifice some (who voluntarily elect to be experimented on, of course) for the greater good.