A key partner in Covax, the organization that has led the effort to bring Covid vaccines to poor and middle-income countries, will stop supplying the shots to a huge part of the global population in the year ahead, and provide them only to the lowest-income nations.

The board of governors of Gavi, the nonprofit that supplies immunizations to developing countries, voted at a meeting in Geneva on Thursday to end Covax support for 37 countries, including Egypt and Indonesia, where hundreds of thousands of people have died from the coronavirus.

Fifty-four other nations, including some of the world’s poorest countries, will continue to receive free Covid shots and funds to help deliver them — if they want them — going into 2025.

The decision reflects the fact that demand for Covid vaccines has plummeted worldwide, and that Gavi has found itself overcommitted to vaccine purchases when countries don’t want them. The continuing vaccination efforts are expected to focus on high-risk groups, including older and immunocompromised people.

Covax has delivered 1.7 billion Covid shots to people in developing nations, in challenging circumstances, but has fallen far short of its goal of ensuring equitable access to the vaccines worldwide. The effort was hobbled at the outset by high-income countries that locked up the initial supply of shots, and later by erratic supply flows and weak delivery systems.

Today, vaccination rates in the countries served by Covax sit at an average of 52 percent of the population receiving initial Covid inoculation. But the figure for sub-Saharan Africa is just 26 percent. Delivery of booster doses has stalled across developing nations, and Covid cases are rising around the world.

“It’s alarming that this decision has been made while the pandemic is still ongoing and without thorough consultation with these countries,” said Kate Elder, the senior vaccines policy adviser for Doctors Without Borders’ access campaign.

But Dr. Anthony Mounts, director of the Covid vaccine introduction program at the Task Force for Global Health, a nonprofit organization that has supported Covid vaccination delivery in 37 developing countries, said the decision seemed inevitable in the face of the across-the-board lack of interest in Covid vaccines he had seen. The World Health Organization estimates that 90 percent of the world population now has some immunity to Covid-19, from vaccination or previous infection.

“In spite of whatever challenges Covax faced, I think just the fact that there was a coordinating mechanism was extremely useful,” Dr. Mounts said. “But it’s time to change our direction and really focus on high-risk groups and what we can do to protect them.”

The 37 countries for which support is ending will receive a one-time payment, which the board described as “catalytic,” to set up their own Covid vaccination programs.

The other 54 are nations that received support from Gavi for routine immunization before the pandemic. If those countries choose to continue with Covid campaigns, Gavi will move to integrate Covid shots into the regular support it offers, ending the emergency program.

“We’re as committed as we were from Day 1 to helping countries reach their national targets and boost the most vulnerable,” Aurelia Nguyen, Gavi’s chief programming and strategy officer, said. “At the same time, we need to plan for any potential worst-case scenario and find ways of gaining efficiencies for countries” by adding Covid-19 shots to regular vaccination programs.

The World Health Organization, another partner in Covax, continues to maintain a goal of vaccinating 70 percent of the population in each country. The W.H.O. did not respond to a request for comment on the Gavi board decision.

Gavi, using funds from rich nations, negotiates purchases with vaccine makers on behalf of Covax, and also channels money to countries to help administer shots. The agency has also received millions of doses of vaccines as donations, the tide of which has ballooned as high-income nations — which have seen their own vaccine programs falter — seek to offload their oversupply.

Budget documents presented to the Gavi board show that the organization has had to renegotiate its vaccine contracts to get out of having to buy hundreds of millions of doses, and that countries have been slow to use the funds they were given to administer the shots.

The Gavi board directed the organization’s staff to update donors early in 2023 on how it suggests using the money currently sitting in the pool to buy vaccines. It also gave broad approval to a plan for Gavi to create a $1.5 billion pandemic preparedness pool.

At the meeting, Gavi’s governors recommitted the organization to trying to catch up on a critical drop in routine childhood vaccinations that has occurred over the course of the Covid pandemic and led to resurgences of diseases including polio and measles.

In addition, the Gavi board voted to restart a vaccination campaign against the human papillomavirus, or HPV, with an investment of $600 million, in an effort to try to reach 86 million girls by 2025 with the vaccine, which aims to prevent cervical cancer.

And, going forward, Gavi will invest in efforts to expand the manufacturing of vaccines in Africa, as part of an effort to prevent the kind of disparity seen early in the Covid pandemic when vaccine nationalism left the continent with no access to shots.