https://www.scientificamerican.com/article/hunt-for-cause-of-vaping-illness-suggests-multiple-mechanisms-of-damage/

Experts remain perplexed about what is causing the nationwide outbreak of mysterious vaping-related lung disease that has affected hundreds and killed at least six people. And even the nature of the disease itself is confounding clinicians and public health officials. The only certainty, they say, is that people should not be vaping anything until they figure it out.

The sigh of relief was almost audible after news emerged in early September of a named culprit: vitamin E acetate. But the U.S. Food and Drug Administration soon dampened that enthusiasm, noting that not all tested samples even contain the oily substance. In fact, no candidate substances have consistently turned up across samples so far.