What a freaking, double whammy nightmare.
People call it a ‘wimpy’ bioweapon because we knew it was coming and only had a few cases initially.
Imagine if it had been released, simultaneously, in 100 of our largest cities. In multiple highly populated/popular spots in each city.
In 3 weeks every ER in nearly every large city would have been full of blue people.
And nobody would have known what did it. Where it came from.
And all your medical people would have it.
Once THAT die off was complete (and it would be spectacular under those conditions...imagine what that scenario would do to law enforcement, the military, food distribution, power/electrical maintenance, etc), then you find out any survivors are sterile.
Complete population replacement in 2 generations.
No bloodshed needed by the aggressor. Just sit back and wait.