Moderna's two-dose vaccine candidate is believed to be "generally safe and well-tolerated" and potentially effective regardless of age, according to new data released by the company on Wednesday.
Study comes as China and Russia push ahead with their own vaccination campaigns.
Howard Koh, who was assistant secretary for health under President Barack Obama, told Newsweek public trust needs to be at the "highest possible standard" for any future COVID-19 vaccine.
Professor Andrew Pollard also said that cases of people being reinfected with the COVID-19 virus had to be closely monitored to ensure the effectiveness of a vaccine.
"China's vaccine research is currently at the forefront," top Chinese virologist Shi Zhengli said in an interview with CGTN, a state-controlled media outlet.
U.S. President Donald Trump suggested that the "deep state" at the FDA deliberately delayed developing a COVID-19 vaccine.
Pharmaceutical giant Sinophram has priced their vaccine candidate at $145, the most expensive vaccine quote yet.
"The Russians, to my knowledge and I'm pretty sure I'm correct, have not been studying this intensively in very large, randomized, placebo-controlled trials," Fauci said during a livestream on Wedneday.
One disease expert said it may be a "more infectious but less deadly" mutation, but others weren't convinced.
The U.S. has continued to move closer to a vaccine for the novel coronavirus, but fewer Americans are saying they'd get one, according to a new poll.
About one-third of American adults aren't planning on getting a new coronavirus vaccine, and Fauci noted it's their "right to refuse."
The CEO of GAVI, the Vaccine Alliance says President Putin's claim to have found a vaccine for the COVID-19 virus needs to be studied.
The vaccine is not coming as soon as some think and Russia has questions to answer about whether its version can work, vaccine CEO says.
The outlined efficacy rates follow guidelines put out by the World Health Organization and the U.S. Food and Drug Administration.
Russia's health ministry said production has started on the vaccine called "Sputnik V," but 52 percent of medics surveyed online said they would not take it yet.
A new coronavirus vaccine is moving forward at an unprecedented pace, but Fauci said speed isn't sacrificing safety.
"We are not at all reducing the regulatory rigor with which we will evaluate and hopefully approve vaccines," the senior U.S. health department official told reporters.
"Once misinformation has taken hold, it is notoriously hard to correct," said Jeanine Guidry, who led a piece of research into how vaccine lies were previously spreading on Pinterest.
"Bottom line is, I'm not pleased with how things are going," Fauci said during a panel on Thursday.
The Russian president announced that the vaccine has been given regulatory approval, sparking concern among experts after less than two months of testing.
"The U.S. standards are so much more stringent," President Donald Trump's counselor said.
Russia's announcement that they registered a new coronavirus vaccine sparked skepticism of its safety and efficacy.
The Russian president said that the vaccine developed at the Gamaleya Institute had been approved by his country's health ministry.
Philippines president said Russia had offered his country the vaccine and promised to be one of the first to receive it to prove it was safe.
If there is no price too high for a successful vaccine, does that change if you've already paid for 100 unsuccessful ones?
While 70 percent or more is better, Fauci said a vaccine that's 50 or 60 percent effective brings added value if it's coupled with public health measures.
Researchers point to a phenomenon called T-cell memory, which may allow white blood cells to attack variations of viruses they have encountered before.
"Usually, vaccines literally take years and years and years to develop," the vice president said.
"We shouldn't be surprised these attacks are happening. What would be surprising is if they stopped," cybersecurity expert Stefan Tanase told Newsweek.
The vice president also said the administration was getting ready to offer vaccines to tens of millions of Americans.