Cuba has had a lung cancer vaccine for years now ...
Cuban Vaccine Tested in Canadian Trial
That may just be coincidental. Cuba is very close to the territorial waters of the US -- better to have a ''friendly'' government there than a hostile one. Cuba is not active in opposition to nor interfering with South American governments, promoting communist ideology in the face of US hegemony <rolls eyes>, Raul Castro is not continuing brother Fidel's foreign policy -- the old USSR Soviet state is not lending military and financial support anymore.
Cuba has everything to gain and the US has little risk in changing its policy. I don't know what they intend to do with the issue of US persons and Cuban expat property claims for property confiscated by the revolution ...