The World Health Organization chief has urged Washington to reconsider its sharp cuts to global health funding, warning that the sudden halt threatened millions of lives.
Tedros Adhanom Ghebreyesus warned on Monday that disruptions to global HIV programmes alone could lead to "more than 10 million additional cases of HIV and three million HIV-related deaths".
"We ask the US to reconsider its support for global health," he told reporters.
Besides triggering the United States pullout from the WHO after returning to the White House in January, US President Donald Trump decided to freeze virtually all US foreign aid, including vast assistance towards boosting health worldwide.
The sudden about-face by the country that has traditionally given most by far has sent the entire humanitarian community into a tailspin.
Tedros warned that the cuts to direct funding for countries through the US Agency for International Development (USAID) and the US Centers for Disease Control and Prevention (CDC) would have a huge impact.
The years-long battles against a long line of diseases, from HIV to measles to polio, would suffer immensely, he said.
TRT Global - The move, part of US President Trump's "America First" policy, halted aid operations worldwide, causing disruptions to humanitarian efforts.
'Severe disruptions'
"There are now severe disruptions to the supply of malaria diagnostics, medicines and insecticide-treated bed nets due to stock-outs, delayed delivery or lack of funding," Tedros said.
"Over the last two decades, the US has been the largest bilateral donor to the fight against malaria, helping to prevent an estimated 2.2 billion cases and 12.7 million deaths," he said.
"If disruptions continue, we could see an additional 15 million cases of malaria and 107,000 deaths this year alone, reversing 15 years of progress."
For HIV, the situation was similar, he said.
The halt to nearly all funding for the US anti-HIV initiative called PEPFAR had already caused "an immediate stop to service for HIV treatment, testing and prevention in more than 50 countries", Tedros said.
"Eight countries now have substantial disruptions to antiretroviral therapy and will run out of medicines in the coming months," he said.
"Disruptions to HIV programmes could undo 20 years of progress, leading to more than 10 million additional cases of HIV and three million HIV-related deaths."
The WHO chief also pointed to the impact on the fight against tuberculosis, warning that nine countries had already reported "failing procurement and supply chains for TB drugs, jeopardising the lives of people with TB".
TRT Global - UN chief Antonio Guterres has pledged efforts to secure funding after the US and European nations reduced aid for over a million Rohingya refugees.
'At risk'
"Over the past two decades, US support for TB services has helped to save almost 80 million lives," Tedros said, adding that "those gains, too, are at risk".
At the same time, on vaccines, he highlighted that the WHO's Global Measles and Rubella Network of more than 700 laboratories, which was funded solely by the United States, "faces imminent shutdown".
" This comes at the worst possible time when measles is making a comeback," he said, noting that measles vaccines in the past 50 years had saved nearly 94 million lives.
"The actions right now are life-threatening," WHO vaccine chief Kate O'Brien told journalists.
"What we're seeing now is just laying the groundwork for hundreds of thousands of deaths that will happen on an annual basis in excess."
Tedros hailed Washington for being "extremely generous over many years", and said it was "of course... within its rights to decide what it supports, and to what extent".
But, he said, "the US also has a responsibility to ensure that if it withdraws direct funding for countries, it is done in an orderly and humane way that allows them to find alternative sources of funding".
"If the US decides not to restore direct funding to countries, we ask it to engage in dialogue with affected countries so plans can be made to transition from reliance on US funding to more sustainable solutions, without disruptions that cost lives."
Tedros said that regardless of whether Washington reinstates its funding, "other donors will need to step up", as would "countries that have relied on US financing".
"WHO has long called for all countries to progressively increase domestic health spending, and that is now more important than ever."
TRT Global - Staff told to "cease all work immediately", with access to buildings and systems barred.