here's nhk's world david mcclure. >> we're going to sit in here. >> reporter: steven palmer has beenfront lines of the coronavirus outbreak in the u.s. he coordinates vaccine research at columbia university medical center in new york. his job puts him in frequent contact with covid-19 patients. >> and -- >> reporter: the work is grueling and dangerous and has taken an emotional toll. >> i'm not the same person i was before this happened. it really was a mixture of terror, grief and loneliness. >> reporter: new york was an early epicenter of the pandemic. and many health care providers were among those who died. in march, the first patients were rushed to the columbia university hospital. >> we were scared to death, you know? when you first walked into the hospital when covid was happening, it was as if it was in the air blowing at you. i washed my hands i would say up to 50 times a day. i put my hand in again and wash like crazy. >> reporter: by mid-march, the hospital was inundated. 25% of the patients in palmer's vaccine trials died, and his psychological turmoil continued to grow.