TBH with this context I don't think he was trying to be insulting to BTS. One can compare BTS making fans super excited and in some cases even faint at the sight of them unto a fever and one can say that is contagious because it happens to allot of people, hence the covid reference. Ill admit under the circumstances being that allot comedians and late night host, use people as the punchlines for hurtful jokes and Asians over the pandemic have been placed into allot of jokes about covid19 i get why some might think that but i don't think the tone of this comment is representative of that. I think it was a joke that was badly placed, that all. and I don't think he is saying BTS represent covid and death. But hey I could be wrong...