Consider that sending already symptomatic people in is retarded in a bio attack. The capability (barring the spread being via violent attack of the already deceased...ARF!) is readily arrested on the ground.
That would hint that the true angle is via some other means, like the early incubation period people have or will arrive shortly and filter out into general population while the quarantine assets are dealing with symptom expressing groups. Or some entirely different approach.
More Clancy.