WASHINGTON — The U.S. is buying 500 million more doses of Pfizer's Covid vaccine that it plans to donate to lower-income countries as President Joe Biden responds to pleas from world leaders to do more to vaccinate the world's population.
The doses will bring the total number of shots the U.S. plans to donate to 1.1 billion, nearly 160 million of which have already been shipped and 200 million of which are expected to go out by the end of the year, an administration official said. The remaining 800 million will be sent out by next September.
"We're nearly 20 months into the pandemic, and this moment really requires urgency to save lives," the official said.
Biden is expected to announce the move Wednesday at a Covid summit the White House is hosting, where he plans to call on other countries to make their own contributions with the goal of vaccinating 70 percent of the world's population by next September, the official said.
"It is a target discussed in the international community, including by the World Health Organization. It is a target we embrace and urge all countries to hit," the official said. "We think it is an important target. It is an ambitious target, but a very important target."
So far, about 6 billion vaccine doses have been given, with rates varying widely among countries. Some, like Portugal and Singapore, have had more than 80 percent of their populations vaccinated, while less than 1 percent of the population has received the shots in other countries, like Haiti and Tanzania. On average, just 20 percent of people in lower-income countries are vaccinated, compared to around 80 percent in the wealthiest countries, according to the WHO.
World leaders criticized the U.S. and other wealthy countries Tuesday at the U.N. General Assembly meeting over their plans to start giving out booster shots before billions of people have yet to get their first doses. The head of the WHO came out in strong opposition to booster shots, and Philippine President Rodrigo Duterte accused the U.S. and other wealthy countries of hoarding vaccines.
"There is a man-made drought of vaccines ravaging poor countries," Duterte said Tuesday. "Rich countries hoard lifesaving vaccines, while poor nations wait for trickles. They now talk of booster shots, while developing countries consider half-doses just to get by."
The WHO has said it will take 11 billion doses to vaccinate at least 70 percent of the world's population, and it has called for a "moratorium" on booster shots until more countries have access to the vaccines.
Biden administration officials have argued that the U.S. can do both — give booster shots to people at home and distribute vaccines globally.
The Food and Drug Administration is expected to give the green light soon to booster shots for people 65 years and older and those at high risk for severe disease. Administration officials have said they have enough supply to give a third dose to every person in the country 16 or older if and when the FDA gives its approval.
The 500 million new Pfizer doses will be made in the U.S. and sold to the federal government at a not-for-profit price, the official said. The contract for the doses hasn't been finalized with Pfizer yet, but the official said it will be completed "as quickly as possible."
Over the summer, the Biden administration announced that it would donate 500 million doses to 100 countries, the largest donation by a single country. The new effort doubles that commitment.
Biden also plans at Wednesday's Covid summit to call on other countries to address the needs of those who do get infected, such as improving oxygen supplies and testing capabilities in poorer countries.
Shannon Pettypiece is the senior White House reporter for NBCNews.com.