Lives are always on the line when it comes to disease, but we have never placed an infinite value on human life. By your logic and morality, the CDC should receive additional funding and staffing until there are 0 deaths from disease every year, regardless of diminishing returns. What if increasing funding and staffing of the CDC by 100x reduced the incidence of flu-related deaths by 10%, would your justification mandate this?
To call the cuts "needless" and justify it by arguing that "there are lives on the line" is simply not a good argument unless you are willing to take the argument to its extreme conclusion. If instead what you are arguing is that you believe that the previous budget and staffing was at a correct figure, and that you believe that the increase in body count that will come as a result of the adjustment of that figure (which I doubt is knowable at this moment at time, or if it is even greater than 0) is not a worthwhile tradeoff, then that is a completely different argument.