Speaking to the BBC, regional director Dr Hans Kluge warned that 500,000 more deaths could be recorded by March unless urgent action is taken.
Dr Kluge said an increase in mask wearing could immediately help.
The warning comes as several nations report record-high infection rates and introduce full and partial lockdowns.
Dr Kluge said factors like the winter season, insufficient vaccine coverage and the regional dominance of the more transmissible Delta variant were behind the spread.
He called for increased vaccine uptake and the implementation of basic public health measures and new medical treatments to help fight the rise.
“Covid-19 has become once again the number one cause of mortality in our region,” he told the BBC, adding “we know what needs to be done” in order to fight the virus.
Dr Kluge said mandatory vaccination measures should be seen as a “last resort” but that it would be “very timely” to have a “legal and societal debate” about the issue.
“Before that, there are other means like the Covid pass,” he said, adding that this is “not a restriction of liberty, rather it is a tool to keep our individual freedom