While there is no international organization and means to distribute the vaccine to the most needy, in the US, we have troves of census data that can pinpoint neighborhoods that are the most at risk - based on age, access to health care, and income.
With a government that actually cares about its people, the HHS can set up pilot sites to vaccinate in those most needy areas. Moreover, the US military has experience in setting up field hospitals for these purposes in Liberia against Ebola. So bottomline is that it is a matter of political will on how we distribute the COVID drugs.