Vaccine exports are underway and on track. However the vaccines require refrigeration which can be logistically challenging in underdeveloped countries.

https://www.wsj.com/articles/u-s-says-it-has-shared-110-mill...

Those poor countries tend to have fewer people at risk due to having younger populations and lower incidences of co-morbid conditions like obesity and diabetes. A recent meta analysis calculated an infection fatality rate of 0.05% in Africa.

https://onlinelibrary.wiley.com/doi/10.1111/eci.13554