Seems relevant:
Even the most potent militarized Anthrax isn't that powerful. We know this from a military Anthrax accident in 1979. A Russian biological warfare plant outside the city of Sverdlosk accidentally released some militarized Anthrax. Thousands of people in the area were infected. But fewer than a hundred died. What was particularly discouraging to Russian military bioweapon scientists was that only one of the dead was of military age and he was already ill from other ailments. All of those that died from the Anthrax were old and usually sick. All the victims had weakened immune systems. Many had lung ailments. The Russians initially denied that there was an accident and did not treat the locals for Anthrax. Later they said the deaths were caused by people eating meat infected with Anthrax, which is a common way for people to die from Anthrax. It was only after the Soviet Union fell apart in 1991 that Western researchers were able to get into the area and interview survivors and discover that people with normal immune systems were able to fight off an Anthrax infection.
Excerpt from:
https://strategypage.com/htmw/....htchem/articles/2021