On Jan. 3, 1978, the Yellow fever vaccine (YF-Vax by Connaught) was licensed in the U.S. The Yellow fever vaccine is a live, attenuated virus preparation made from the 17D yellow fever virus strain. The 17D vaccine has proven to be extremely safe and effective.

The 17D strain is grown in chick embryo inoculated with a seed virus of a fixed-passage level. The vaccine is freeze-dried supernate of centrifuged embryo homogenate, packaged in one-dose and five-dose vials for domestic use.