multiple myeloma, a blood cancer that can significantly weaken the body's immune system. here with us with more is doctor hotez from baylor college of medicine. fully vaccinated, understands he has this cancer and is being very careful and yet this can happen. walk us through it. >> yeah. that's a sad day for me as well, john, because in the decade i was microbiology chair at gw, secretary powell, general powell was a pretty frequent visitor to george washington university. the president then used to invite him quite a bit and i got to know him somewhat so this is tough for a number of us. you know, with multiple myeloma, it's -- it's a blood cancer, it's a cancer of a type of white blood cells called the plasma cell that's involved in producing antibodies so people don't produce the antibodies that they don't need to in order to fight infection because