It depends. I know that's a vague response, but it really varies. A lot of work done at places like the CDC and WHO is primarily administrative work. You're not working with poor people in Africa or seeing patients. You're on computers writing policy briefs, evaluating health programs, making powerpoints, emailing people worldwide to forge partnerships, etc. So yea, it's office work done on computers, but it's what you do on the computers that's important [like if you're contacting health ministries in developing countries and helping them with their health programs, that's really meaningful work].