Then you haven't thought very hard. "At all costs" is way, way, way too strong. We already have viruses that are much more infectious and deadly than SARS-CoV-2, for example Ebola, and we have not taken this "at all costs" attitude towards them. We expend some effort towards fighting and containing them, but only in proportion, since there are so many other things we also need to expend effort towards doing.

> the ball is in science's court to prescribe a course of action

No, it isn't. Choosing a course of action requires attaching value to different possible future states of affairs. Science cannot do that. It requires value judgments, and science cannot make value judgments.

To take your example, science can to some extent tell you what will happen if you impose mandatory vaccination or if you don't--although since much of what needs to be predicted involves second, third, fourth, and higher order effects and includes various aspects of human psychology and free choice that are not at all well understood scientifically, science's ability to make accurate predictions about such outcomes is limited. But science cannot tell you which of those two possible states of affairs is to be preferred, all things considered.