Poorer countries are increasingly losing health care workers to wealthier ones as the latter seek to shore up their own staff losses from the COVID-19 pandemic, sometimes through active recruitment, the World Health Organization said on Tuesday.

The trend for nurses and other staff to leave parts of Africa or Southeast Asia for better opportunities in wealthier countries in the Middle East or Europe was already under way before the pandemic but has accelerated since, the U.N. health agency said, as global competition heats up.

"Health workers are the backbone of every health system, and yet 55 countries with some of the world's most fragile health systems do not have enough and many are losing their health workers to international migration," said Tedros Adhanom Ghebreyesus, the WHO director-general.