and a genuine side effect.
The vaccine was against Bubonic Plague. In its Pneumonic form it can kill the doctor before his patient and it has been weaponized.
After I left the Regular Army in 1985 I joined a Reserve unit in New Jersey for a few months prior to moving to Indiana. The unit was mostly a joke but was attached the to the Rapid Deployment Force and summer camp was at Fort Bragg that year.
One fine morning we counted off in formation, One, Two, Repeat.
Those of us who were Ones marched off to the clinic for Plague shots. Trust you me, it hurt, and it hurt for days. Ask any nurse.
The next day the Twos and the stragglers marched off to the clinic for their plague shots.
The next day the annual Physical Training Test was administered to all.
It's a high stakes test and every single Two failed the Push Up portion. So did most of the Ones.
In reality about half would have failed either way but when nearly everyone fails a test the clerks go to work. Everyone passed.