When Bruce Wayne trained himself to become learning multiple martial arts and exercising his body until it was capable of amazing feats. And it meant strengthening his immune system until it could shrug off practically any disease.
After all, when your rogue’s gallery includes villains like the Joker, the Scarecrow, and Poison Ivy who use toxins and disease as their weapon of choice, not every battle can be decided by a quick punch or a brilliant deduction. Sometimes, the best defense… is a planned immunity to a potentially fatal illness or disease.
So, how powerful did Bruce Wayne manage to make his immune system? Well, most fans would agree that Bruce already had a remarkably healthy constitution to begin with. Study and training certainly took him far, but Bruce wouldn’t have become the Bruce Wayne gained the equivalent of several medical degrees after auditing multiple classes at some of the world’s finest universities.
Still, when you’re training to become a Dark Knight, you need to go the extra mile, and Bruce Wayne definitely did that. In Batman #681, Bruce flashes back to an early training session where one of his instructors gave him a poisoned cup of tea and informed him he had less than two minutes to live. Ever the master detective, Bruce revealed he’d already suspected what was going on and switched the cups when his instructor wasn’t looking, calling it a “force of habit.”
What Bruce says next, however, reveals just how prepared he was in the event that he had drunk the tea. According to Bruce, he carries antidotes for all poisons he’s not already immune to, revealing that he’s taken precautions to vaccinate or immunize himself against multiple diseases. He adds that he can also usually improvise if face with something unfamiliar. Unwilling to kill even in the face of such treachery, he chooses to use one of the antidotes on his person to save his instructor from death.
Bruce’s obsessive need to prepare for all these contingencies served him well in the same issue, as his enemies wound up pumping him full of multiple toxins (including a Joker toxin), strapping him in a straitjacket and burying him alive. While understandably very sick, Bruce’s immune system still managed to keep him alive even as he freed himself from his bonds and bench pressed 600 pounds of loose soil to dig himself out of his own grave.
Granted, Bruce’s immune system can’t protect him against every virus or toxin, and he’s been known to fall victim to something even his constitution or antidotes can’t immediately shake off. Even so, his need to be prepared for any situation (it’s a given that he’d be wearing a full-face mask during the COVID-19 pandemic), ensures Batman will be thinking ten steps ahead of his enemy. Even if that enemy is a virus.
