According to Tedros, unequal distribution of vaccines has allowed the virus to continue spreading, thus increasing odds of a variant emerging that could render these treatments ineffective.
"Inequitable vaccination is a threat to all nations, not just those with the fewest vaccines," he warned in his latest media briefing from WHO headquarters in Geneva.
As of Monday, there were more than 173 million confirmed cases of covid-19 globally, including 3.7 million deaths.
"Increasingly, we see a two-track pandemic: many countries still face an extremely dangerous situation, while some of those with the highest vaccination rates are starting to talk about ending restrictions," he told journalists.
So far, nearly 44 per cent of doses have been administered in richer countries.
In poorer nations, the figure is just 0.4 per cent.
The UN has been pressing governments to share their excess doses to the global vaccine equity initiative, COVAX.