Threlkeld said it is believed there are less than 20 adults that have been diagnosed with the condition, and they had not been vaccinated. Last October, the CDC released a report on MIS-A.
"With the exception of possibly one other person in the country, no one else has been reported to have had this after having the infection and being vaccinated," said Threlkeld.
The rarity of the situation is also one reason the CDC is involved. In addition to an autopsy, Threlkeld said additional testing is being done.
Medical experts said MIS-A creates a severe inflammatory response in a the body, causing organs to malfunction.