Delivering a vaccine first is a matter of national prestige for the Kremlin as it tries to assert the image of Russia as a global power capable of competing with the US and China.
Trials are pivotal for establishing the safety and effectiveness of the vaccines. Not all patients who volunteer for clinical trials are eligible to participate.
Yet overnight, after returning from a trip to North Carolina where he promoted efforts to develop a COVID-19 vaccine, Trump retweeted a series of tweets advocating for hydroxychloroquine.
The loss of 969 lives was the biggest increase since June 10, with Florida, South Carolina and Texas all reporting their biggest one-day spikes on Thursday.
His comments follow promising early stage data for the Moderna Inc's coronavirus vaccine, released on Tuesday, that was developed by scientists at the National Institute of Allergy and Infectious Diseases, which Fauci directs.
The Republican president, seeking re-election in November, has been increasingly critical of government health officials and their guidance as a steady rise in infections threatens the easing of shutdown restrictions across the country.
Fauci warned that the daily increase of new cases in the United States, currently around 40,000, could reach 100,000 if people do not adhere to social distancing guidelines and wear masks.
So far, more than 114,000 people have died from COVID-19 in the United States, according to a Reuters tally. About half a dozen US states are grappling with a rising number of coronavirus patients filling hospital beds.
WHO's technical lead Maria Van Kerkhove tried to clear up “misunderstandings” on the pandemic about comments she made that were widely understood to suggest that people without COVID-19 symptoms rarely transmit the virus. She insisted on Tuesday that she was referring only to a few studies, not a complete picture.
Fauci, director of the National Institute of Allergy and Infectious Diseases, told a U.S. Senate panel that the virus epidemic is not yet under control in areas of the nation.
Fauci, a member of the coronavirus task force charged with shaping the response to COVID-19, which has killed tens of thousands of people in the U.S., is testifying via video conference after self-quarantining as a White House staffer tested positive for the virus.
Trump, speaking to reporters at the White House, defended his decision to block the nation's top infectious disease expert from appearing before the House, saying he was being set up by Democrats who hate him and want to win back the White House in November's presidential election.
Trump, who on Sunday fuelled speculation by retweeting a critical comment with the hashtag #FireFauci, sought to draw a line under the latest White House turmoil.
Official statistics, which exclude deaths outside of hospitals, have understated the actual number of people who have succumbed to COVID-19, the respiratory disease caused by the new coronavirus, health experts said.
The Republican president in the past has repeated critical tweets of officials or enemies rather than make the criticism himself.