We estimate that at least 115,000 health and care workers have paid the ultimate price in the service for others," WHO Director-General Tedros Ghebreyesus said.
"We will lose many more as long as the pandemic rages," he added.
"Health and care workers do heroic things. But they are not superheroes. They're humans, like the rest of us. They sweat and swear. They laugh and cry. They feel and hope many feel frustrated. Helpless," said Tedros.
He said they are affected by a lack of access to personal protective equipment, vaccines, and tools to save lives.
"Globally, we remain in a fragile situation. No country should assume it is out of the woods."
The World Health Assembly is the decision-making body of WHO and meets each year typically. In 2021, it is meeting virtually for the second time due to the pandemic.
Also addressing the meeting, the UN chief Antonio Guterres said," We are at war with a virus. We need the logic and urgency of a war economy to boost the capacity of our weapons."
He said that COVID-19 has brought a "tsunami of suffering."
Switzerland's Health Minister Alain Berset made the opening speech of the gathering in Geneva.
"As we have sought to grapple with the COVID-19 pandemic, we recognize that we are now facing new threats," said Berset.
"Of course, we see the proliferation of variants of the virus, but we also see threats related to the socio-economic consequences of the crisis."