On the variety show "Stargazing", Yunho guested and they spoke about the infamous incident where an anti-fan spiked superglue a drink and gave it for Yunho to drink.
Yunho said that he doesn't actually recall that much from that incident. It was his habit then to drink things in one shot, so when the fan gave it to him, he drank it all before finally realizing there was a strange scent to it. He then fainted, and later on the members told him that he had vomited blood.
A fan on the show also shared that he had experienced a similar situation, when a student had poisoned his drink as well. However, after reading a message that Yunho wrote after the attack, saying that he will work harder, the fan gained courage to continue teaching.
It must have been terrifying for both of them, but I'm glad Yunho was able to positively influence others with his humble mentality!