Then let me demonstrate the point by leaning all the assumptions in the opposite direction.

Assumption: The vaccine has an efficacy of 60%. This will be altered to 90%, which it can reach for a healthy adult.

Assumption: There is a 0.5% chance of a hospital stay if you get sick. This will be put up to 1%.

Assumption: There is a 0% chance of death, given that you are sick enough to require a hospital stay. This will be put up to 50%.

Assumption: Your immune system gives you a natural 95% chance of avoiding the flu. This will be reduced to 92%. (That may still be too high).

Result:

Flu shot: $30+(0.008*1000)+(0.00004*7000) = $38.28, plus 0.00002% chance of death

No flu shot: $0+(0.08*1000)+(0.0004*7000) = $82.80, plus 0.0002% chance of death