The US government will first give Americans Covid-19 vaccines, but any surplus would be shared with the world, President Joe Biden said on Wednesday after earlier announcing plans to procure an additional 100 million doses.

"We're going to start off and ensure Americans are taken care of first, but we're then going to try to help the rest of the world," Biden told reporters following an earlier announcement to secure more vaccines with the chief executives of Johnson & Johnson and Merck.

"If we have a surplus, we're going to share it with the rest of the world," Biden said, adding that the United States had already committed to...