Apparently it has been covered.
Dug this out of the Horrors thread. Spoilers below for the Novel The Forever Drug by Lisa Smedman.
"this issue was resolved in a novel : The Forever Drug by Lisa Smedman. Apparently, the vaccine is meant to activate the longevity genome in all metahumanity, they would live forever unless killed via the usual methods...
the vaccination plan failed due to a run resulting int the destruction of the factory/ doctors/ loss of data... nothing was left aside.
Lofwyr was said to be behind it ...."
For what it is worth, if that was in the fruitcake it would be one HELL of a fruitcake to get your hands on. (Since this thread became focused on the insides of the cake at some point)
Alexis
*smiles*
PS- I am about to Necro the Horrors thread too.