Global tensions are simmering over the race for a coronavirus vaccine.
France as slammed pharmaceuticals giant Sanofi for suggesting the United States would get any eventual vaccine first.
Scientists are working at breakneck speed to develop a vaccine for COVID-19, the disease caused by the virus, which has killed more than 300,000 people worldwide and pummelled economies.
World leaders were among 140 signatories to a letter published Thursday saying any vaccine should not be patented and that the science should be shared among nations.
"Governments and international partners must unite around a global guarantee which ensures that, when a safe and effective vaccine is developed, it is produced rapidly at scale and made available for all people, in all countries, free of charge," it said.
But a row erupted in France after drugmaker Sanofi said it would reserve first shipments of any vaccine it discovered to the United States.
The comments prompted a swift rebuke from the French government -- President Emmanuel Macron's office said any vaccine should be treated as "a global public good, which is not submitted to market forces."
Sanofi chief executive Paul Hudson said the U.S. had a risk-sharing model that allowed for manufacturing to start before a vaccine had been finally approved -- while Europe did not.
"The U.S. government has the right to the largest pre-order because it's invested in taking the risk," Hudson told Bloomberg News.
Macron's top officials are scheduled to meet with Sanofi executives about the issue next week.
The search for a vaccine became even more urgent after the World Health Organization said the disease may never go away and the world would have to learn to live with it for good.
"This virus may become just another endemic virus in our communities and this virus may never go away," said Michael Ryan, the UN body's emergencies director.
—SUSAN STUMME with Danny Kemp
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