Answer
When $x\rightarrow 100, f(x)\rightarrow \infty$
Vertical asymptote: $x=100$
Work Step by Step
We are given the function:
$$f(x)=\dfrac{130x}{100-x}.\tag1$$
The domain of the function is $[0,100)$.
From the function we notice that for $x=60$ the cost is $195$ million, for $x=80$ it raises at $520$ million, for $x=90$ it is greater than $1$ billion, so it becomes prohibitive.
From the graph we notice that when $x$ approaches $100$ from the left, the value $f(x)$ increases indefinitely (the graph has a vertical asymptote $x=100$).
The conclusion is the same: inoculating all population is not possible due to infinite cost and practical impediments (like medical issues which forbid inoculation against flu for some persons, social issues, technical issues and so on).
