The two directors condemned what they dubbed a "self-defeating" strategy, which they say allows the virus to mutate further, undermining vaccination efforts and a chance at global economic recovery.
Currently, 130 different countries, totaling a population of 2.5 billion, have yet to administer the vaccine at all, the two directors stated.
The two organizations call on world leaders to "look beyond their borders" to find a vaccination strategy "that can actually end the pandemic and limit variants."
They urged countries to priorities health workers first, and added that while health workers have been trained, a supply of vaccines is still not available.
They further called on manufacturers to allocate the vaccines equitably and share manufacturing and efficacy data with the WHO, as well as funding the Access to COVID-19 Tools (ACT) Accelerator and its vaccine branch COVAX to support lower-income countries.
"COVID-19 has shown that our fates are inextricably linked," they said. "Whether we win or lose, we will do so together.”
Multiple vaccines have been approved for use against COVID-19, such as the ones made by Pfizer, Moderna, AstraZeneca and the Russian-made Sputnik IV.
According to GitHub, Israel leads the world in vaccines per capita, having administered 5.83 million doses administered, with an average of nearly 64.42 out of every 100 people. In terms of sheer numbers, the US leads with over 43 million doses administered.