Brian in Jeollanam-do broke the story
, and the Midnight Runner has done an excellent podcast
with the teacher supposedly affected.
The Canadian teacher, only identified as 'Mark' had been on vacation in Thailand, then returned to Korea. He began feeling sick about 4-5 days after returning to Korea (though 'Mark' never mentions having a week of quarantine, which has quickly become standard procedure for most schools too worried about foreign teachers getting sick). From the podcast, his hagwon asked him to come into work even though they knew he was sick.
Now here's a story that makes us scratch our heads.