OP's analysis has a term for quality of life issues stemming from the illness; it just happens to be a fourth of the magnitude of lost productivity ($200 vs. $800). The latter ends up dominating the calculation. There's also a term for the costs of palliative care, estimated at $100, but that looks a little sketchy to me; a package of Theraflu and some tissues and cough drops would run maybe $20.

On the other hand, Lumifer's health insurance would probably cover the flu shot. Mine would.