Sadly I have no idea what activated it, but it happened shortly before the trip to the sewers w/ Henry and his little dude. It may have happened during the escape from the truck, but I am not sure.
The glitch causes the health- and if underwater also the air-bar to be completely empty. It seems like I'm also losing air way less fast, but that might be wrong approximation by me. The glitch does not deactivate after cutscenes, saves, autoreloads and death.
While the glitch is active it is not possible to observe your current health, so it is pretty annoying...
Played on hard mode.