In the latest Senate package targeted at stopping the coronavirus, U.S. lawmakers dropped nearly all funding for curbing the virus beyond American borders, a move many health experts slammed as dangerously short-sighted.

They warn the suspension of COVID-19 aid for poorer countries could ultimately allow the kind of unchecked transmission needed for the next worrisome variant to emerge and unravel much of the progress achieved so far.

The U.S. has been the biggest contributor to the global pandemic response, delivering more than 500 million vaccines, and the lack of funding will be a major setback. The money has paid for numerous interventions, including a mass vaccination campaign in the Cameroonian capital that saw hundreds of thousands of people get their first dose, as well as the construction of a COVID-19 care facility in South Africa and the donation of 1,000 ventilators to that country.

Other U.S.-funded vaccination campaigns in dozens of countries, including Uganda, Zambia, Ivory Coast and Mali, could also come to a grinding halt.

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“Any stoppage of funds will affect us,” said Misaki Wayengera, a Ugandan official who heads a technical committee advising the government on the pandemic response. He said Uganda has leaned heavily on donor help — it received more than 11 million vaccines from the U.S. — and that any cuts “would make it very difficult for us to make ends meet.”

“This is a bit of a kick in the teeth to poor countries that were promised billions of vaccines and resources last year in grand pledges made by the G7 and the G20,” said Michael Head, a global health research fellow at Britain’s Southampton University.

“Given how badly we’ve failed on vaccine equity, it’s clear all of those promises have now been broken,” he said, adding that without concerted effort and money to fight COVID-19 in the coming months, the pandemic could persist for years.

While about 66% of the American population has been fully immunized against the coronavirus, fewer than 15% of people in poorer countries have received a single dose. Health officials working on COVID-19 vaccination in developing countries supported by the U.S. say they expect to see a reversal of progress once the funds disappear.

“Vaccination will stop or not even get started in some countries,” said Rachel Hall, executive director of U.S. government advocacy at the charity CARE. She cited estimates from USAID that the suspended funding would mean scrapping testing, treatment and health services for about 100 million people.

Although vaccines are more plentiful this year, many poorer countries have struggled to get shots into arms and hundreds of millions of donated vaccines have either expired, been returned or sat unused. To address those logistical hurdles, U.S. aid has financed critical services in countries across Africa, including the safe delivery of vaccines, training health workers and fighting vaccine misinformation.

For example, in November the U.S. Embassy in the Cameroonian capital set up a tent for mass vaccination: Within the first five days, more than 300,000 people received a dose. Those kinds of events will now be harder to conduct without American funds.

Hall also noted there would be consequences far beyond COVID-19, saying countries struggling with multiple disease outbreaks, like Congo and Mali, would face difficult choices.

“They will have to choose between fighting Ebola, malaria, polio, COVID and more,” she said.

Jeff Zients, the outgoing leader of the White House COVID-19 task force, expressed regret the legislation doesn’t include resources for the international pandemic fight, noting that would also compromise efforts to track the virus’ genetic evolution.

“It is a real disappointment that there’s no global funding in this bill,” he said. “This virus knows no borders, and it’s in our national interest to vaccinate the world and protect against possible new variants.”

Still, Zients announced the U.S. would be the first to donate “tens of millions” of doses for children to poorer countries and said more than 20 nations had already requested the shots.

J. Stephen Morrison, director of the Global Health Policy Center at the Center for Strategic and International Studies in Washington, lamented that lawmakers were erring on the side of optimism about the pandemic precisely when another surge might be arriving.

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“We’ve made that mistake several times in this pandemic. And we may be making that mistake again,” he said. In recent weeks, COVID-19 cases caused by the hugely infectious omicron subvariant BA.2 have surged across Europe, and American officials say they expect a U.S. spike soon.

Other experts worried the suspension of U.S. global support for COVID-19 might prompt officials to drop current vaccination goals. The World Health Organization had set a target of immunizing at least 70% of people in all countries by the middle of this year, but with nearly 50 countries vaccinating fewer than 20% of their populations, hitting that target is highly unlikely.

Instead, some organizations like the Rockefeller Foundation have pushed for officials to “refocus vaccination goals away from vaccinating 70% of all adults by summer to vaccinating 90% of those most at-risk in each country,” in what some critics say is an implicit acknowledgment of the world’s repeated failures to share vaccines fairly. Others point out there shouldn't be competing vaccine targets and that health authorities simply need to do more, rather than adjusting global goals.

In Nigeria, which has so far received at least $143 million in COVID-19 aid from the U.S, authorities dismissed suggestions their coronavirus programs would suffer as a result of lost funding. The Nigerian president’s office said help from the U.S. was mostly “in kind” via capacity building, research support and donations of laboratory equipment and vaccines. “We are confident that this will not cause any disruption of our current programs,” it said.

However, others warned the U.S. decision set an unfortunate precedent for global cooperation to end the pandemic at a time when fresh concerns like the Ukraine war are drawing more attention.

U.S. President Joe Biden originally planned to convene a virtual summit in the first quarter of this year to keep international efforts on track, but no event has been scheduled.

“In light of the ongoing war in Ukraine, we don’t yet have a final date for the summit, but we are working closely with countries and international partners to advance commitments,” said a senior Biden administration official who was not authorized to comment publicly.

As of this month, WHO said it had gotten only $1.8 billion of the $16.8 billion needed from donors to speed access to coronavirus vaccines, medicines and diagnostics.

“Nobody else is stepping up to fill the void at the moment and the U.S. decision to suspend funding may lead other donor countries to act similarly,” said Dr. Krishna Udayakumar, director of Duke University’s Global Health Innovation Center.

Keri Althoff, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health, described the U.S. suspension of funding as “devastating.”

“How could this possibly be what we’re debating right now?" she asked. “It’s a moral obligation to the rest of the world to continue to contribute to this global pandemic response, not only to protect ourselves but to protect people from around the world.”