Fun fact! Cuba has a vaccine for lung cancer - yes, it works and has been independently verified. No, you can’t have it because embargo.
EDIT: vaccine here isn’t actually what I thought. In this case it is a treatment to be used for certain kinds of lung cancer, not a preventative measure as we are used to thinking of Vaccine. Thanks to the comment below for going through it and pushing me to do proper research.
While my initial take was a glib link to a wikipedia page and not thoroughly researched, I do sill believe that the embargo has directly caused this treatment to come to market in the west as the levels of cooperation are non-existent. It has been used for 7 years in Cuba but is only now entering Stage 3 trials in the US.