The United States’ future in the World Health Organization is again in flux with President-elect Donald Trump returning to the White House.

If the U.S. withdraws from the global health body, as Trump attempted to do in his first term, the WHO could lose its top government donor and hundreds of millions of dollars in contributions.

In exchange, America could lose access to the global network that sets the flu vaccine’s composition every year, and U.S. drugmakers could lose the WHO’s help in selling their products, current and former U.S. government officials say.

How it would work: The president can end U.S. membership in the WHO, an arm of the United Nations, without Congress’ consent as long as he gives a one-year notice and continues paying dues in that year, according to a 1948 resolution.

Trump’s transition team declined to comment directly to an inquiry about his plans.

Why it matters: The U.S. provides about a quarter of the WHO’s core annual budget as a mandatory membership fee but often gives more — with the figure ranging from $163 million to $816 million in recent years, according to health policy think tank KFF.

The WHO could lose all that money at a time when it finds itself stretched by health emergencies around the world, from ongoing mpox and cholera outbreaks in Africa to the diseases spreading as a consequence of war in Gaza and Sudan, among other places.

In July 2020, Trump sent a letter to WHO Director-General Tedros Adhanom Ghebreyesus notifying him of the U.S. intention to withdraw within a year. Trump accused the WHO at the time of helping China mislead the world about the spread of Covid-19.

But Trump was defeated in that year’s election, and when President Joe Biden took office in January 2021, he reversed Trump’s decision.

Should Trump decide to withdraw again, he has the time.

What’s next? Unlike in 2020, the WHO could offset some of the financial losses if Trump decides to withdraw.

In May, it launched an investment round seeking some $7 billion “to mobilize predictable and flexible resources from a broader base of donors” for the WHO’s core work between 2025 and 2028.

The WHO did not respond to a request for comment on a potential U.S. withdrawal and its implications.