GENEVA — U.S. Secretary of State Antony Blinken has kicked off an appeal to other countries to help inject $2 billion more to the U.N.-backed program to ship coronavirus vaccines to the world’s poorest countries.

The United States is co-hosting a pledging and donor conference Thursday, bringing together four presidents, three prime ministers and other dignitaries to help buttress the $6.3 billion already raised for the U.N.-backed COVAX program.

Blinken laid out a goal to raise COVAX’s target of vaccinating 20% of populations in the affected countries to 30%, with the addition of $2 billion in funds. The COVAX effort has been providing millions of vaccine doses to 92 of the world’s poorest countries.

“We recognize that as long as COVID is spreading and replicating anywhere, it poses a threat to people everywhere,” Blinken says.

Donors were expected to chip in either funds — prime minister Stefan Lofven announced Sweden was increasing its contribution to COVAX from $20 million to $280 million — or announce plans to share doses with the low- and middle-income countries.

Blinken highlighted the Biden administration’s contribution of $2 billion to COVAX in March and its plans to add another $2 billion through 2022.