What is the definition or description of: yf vax?

Yellow Fever Vaccine: Yf vax is the vaccine that is used for yellow fever vaccination. This product is made only by sanofi-pasteur, and only licensed physicians that are registered with their state health departments can order this vaccine. This is a live but attenuated vaccine, and thus should not be given to people with impaired immunity.

Yellow fever vaccine: This is a live vaccine that protects against the yellow fever virus. A live vaccine means that it is a weakened form of the actual virus, so people with weakened immune systems (hiv+, on steroids, etc) can actually get ill from it. A single injected dose protects for up to 10 years.