Thats a horror story, but the actual horror is society picking not up on this until its too late for alot of lifes. This is one of the incidents, that a centralized health system with data mining could have picked up easily.
Both of those stories are from the 80s, when hard drives were the size of washing machines and an internet connection was an unlikely thing to have outside the military and larger scientific institutions (e.g., CERN).
I read the Wikipedia article... it's scary and sadly a number of people died or were injured... but then I think about something like the Covid pandemic and, compared to that, the number of deaths from radioactive sources like this basically round to zero.
If people are strongly affected by the radiation, then it's probably not going to be that long until the problem is tracked down and dealt with.
I suppose the worst case scenario would be if the radiation was in a place where it wasn't affecting people as acutely and lots of people were passing nearby it, such that the existence of the radiation wouldn't be as obvious or as easy to track down.
Stuff of nightmares.