People are becoming weary of the coronavirus pandemic but should remain vigilant and continue to take precautions while the world awaits a vaccine, World Health Organization chief Tedros Adhanom Ghebreyesus said on Thursday.

Eleven months into the pandemic that has killed more than 1.2 million people, derailed economies and turned daily lives upside down around the world, he said relying on promising but as-yet unproven vaccines was a risky bet.

“We may be tired of COVID-19 but it is not tired of us. European countries are struggling but the virus has not changed significantly, nor the measures to stop it,” Tedros told the Paris Peace Forum.

A recent resurgence in coronavirus infections has led many countries to adopt new lockdown measures to contain the spread of the virus and protect their creaking healthcare systems.

On Monday, U.S. drugmaker Pfizer and German partner BioNTech SE said a vaccine they are developing was 90% effective against COVID-19, based on initial results from its large, late-stage trial

The results need to be confirmed by safety data.

“A vaccine is needed urgently, but we cannot wait for a vaccine and put all our eggs in one basket,” Tedros said on Thursday, repeating a call for any COVID-19 vaccine to be shared fairly with poor countries.