"Despite the growing number of vaccine options, current manufacturing capacity meets only a fraction of global need," the WHO director-general said in a piece published in Foreign Policy magazine.
"Allowing the majority of the world's population to go unvaccinated will not only perpetuate needless illness and deaths and the pain of ongoing lockdowns, but also spawn new virus mutations as COVID-19 continues to spread among unprotected populations," he wrote.
Tedros raised the issue when expressing concerns that some big countries are racing to get COVID-19 vaccines, leaving the world's least developed countries only to wait and watch.
The global scramble for shots comes as more troubling data emerges on new variants of the coronavirus, which is known to have infected more than 101 million people worldwide.
The variants first detected in Britain, Brazil and South Africa are believed to be more contagious.
Source: Agencies