Pressure mounts on G20 nations to get Covid vaccines to poorer countries.

As President Biden and other leaders gathered on Saturday to discuss plans to protect against future pandemics, health experts and activists say that rich nations are still not doing enough to help people in poor nations survive the current one.

White House advisers said the president would spend his time at this weekend’s Group of 20 summit focused on fixing supply chains, securing a blessing on a global tax deal, and pushing to explore debt relief and emergency financing for poor countries whose economies have been battered by the pandemic.

From the start of the summit, leaders tried to telegraph the importance of ending the pandemic: During a group photo, they were joined on the dais by doctors in white coats and first responders from the Italian Red Cross. Prime Minister Mario Draghi of Italy, in his remarks opening the meeting, also pointed to the stark disparity in access to vaccines between richer and poorer countries.

While wealthy nations are offering people third vaccine doses and increasingly inoculating children, poor countries have administered an estimated four doses per 100 people, according to the World Health Organization.

Yet although Mr. Biden has promised to make the United States an “arsenal of vaccines” for the world, White House officials tried to manage expectations heading into the summit that there would be any large announcements on vaccine sharing.

Jake Sullivan, the president’s national security adviser, told reporters on Air Force One en route to Rome that “the main thrust of the effort on Covid-19 is not actually traveling through the G20.” He said that a virtual summit that Mr. Biden convened in September had set “more ambitious targets” for countries to pledge shared doses of the vaccine.

Although Secretary of State Antony Blinken is scheduled to host a meeting of dozens of countries and nongovernmental organizations later this year to secure commitments on vaccine sharing, Mr. Sullivan said the focus for the G20 was on the future.

Mr. Biden said in June that the United States would buy 500 million Pfizer-BioNTech coronavirus vaccine doses for poorer nations. He followed up in September by announcing an additional 500 million Pfizer doses, along with the promise of an additional $750 million for vaccine distribution, roughly half of it through a nonprofit involved in global vaccinations.

Only about 300 million of those doses are expected to be shipped this year, a number that experts say falls short of the amount needed for meaningful protection against the virus.

“You really have a failure of developed countries’ leadership post-Covid,” said Célia Belin, a visiting foreign policy fellow in the Center on the United States and Europe at the Brookings Institution. “This is going to have consequences.”

Since arriving in Rome, Mr. Biden has already heard a personal appeal to do more: During a meeting at the Vatican on Friday, Pope Francis pushed the president on the issue, a senior official said after the meeting.

And in an open letter to the G20, the head of the World Health Organization, Dr. Tedros Adhanom Ghebreyesus, urged the leaders of the world’s largest economies to “to help stem the pandemic by expanding access to vaccines and other tools for the people and places where these are in shortest supply.”