Too many "accidentally-on-purpose" actions being made to believe this is a mistake! The people that were able to walk out were released to be able to spread this further, just as the Cruise ship victims were kept in the ship to be sure as many as possible could get it, or at least be carriers, then sent to points worldwide, to be sure it is now un-contained worldwide!!!
Get ready people! This bio-engineered weapon IS coming to your town; it's just a matter of time now, so build your immune system up!