The White House today pushed back on concerns expressed by the World Health Organisation after a United States health official said a coronavirus vaccine might be approved without completing full trials.
Separately the Trump Administration said it will not join a global effort to develop, manufacture and distribute a coronavirus vaccine, in part because the WHO is involved.
The Washington Post reports that the decision to spurn the Covax facility could shape the course of the pandemic and America's role in health diplomacy.
Covax aims to speed vaccine development and avoid the hoarding of supplies. It would secure doses for all countries and distribute them to the most high-risk people. The plan is backed by New Zealand, Britain, Japan, Germany, Canada and the European Commission. Countries are still able to pursue bilateral deals with firms on vaccines.
"The United States will continue to engage our international partners to ensure we defeat this virus, but we will not be constrained by multilateral organisations influenced by the corrupt World Health Organisation and China," White House spokesman Judd Deere said in a statement.
"This President will spare no expense to ensure that any new vaccine maintains our own FDA's gold standard for safety and efficacy, is thoroughly tested, and saves lives," he said.
The decision cuts the US off from securing doses from a group of possible vaccines.
"America is taking a huge gamble by taking a go-it-alone strategy," Lawrence Gostin, a professor of global health law at Georgetown University, told the Washington Post.
US Food and Drug Administration Commissioner Stephen Hahn told the Financial Times in an interview that the FDA was prepared to authorise a coronavirus vaccine before late-stage Phase Three clinical trials were complete, as long as officials are convinced that the benefits outweigh the risks.
Yesterday, WHO officials said moving too quickly to make a vaccine widely available could pose risks.
"If you move too quickly to vaccinate ... millions of people, you may miss certain adverse effects," said Mike Ryan, the head of WHO's emergencies programme.