they do these drills all the time... Like wargames or hospitals “disaster drills” they are held to help people figure out the problems they face and what needs to be improved.
Johns Hopkins has been having these medical “war game” scenarios since before 911... the last one they did was on a possible corona virus outbreak but in the past they have done similar scenarios for smallpox (Dark Winter) influenza and SARS.
here is a list of them
http://www.centerforhealthsecurity.org/our-work/exercises/
The Dark Winter one was held shortly before 911 was about a smallpox outbreak caused by terrorists. So after 911,when many in the government worried that Saddam would set lose a smallpox attack, they already had plans intact on who to inoculate first and how to set up a clinic etc etc and these were sent to various public health clinics all over the USA.
(I was the doc in our public health clinic tasked to teach the plan, since I had expertise in doing this type of stuff when I was in Africa).