Director of the National Institute of Allergy and Infectious Diseases Dr. Anthony Fauci said Wednesday that, while there is never a guarantee for a safe or effective vaccine, he is confident about how well the process is going in developing more than one COVID-19 vaccine candidate.

In an interview on ABC's Good Morning America, Fauci said early vaccine testing in animals and Phase I testing in humans “looks quite promising,” adding he is “cautiously optimistic” as we head into the summer.

CLICK HERE FOR FULL CORONAVIRUS COVERAGE

As advanced clinical trials begin, Fauci explained there may be “at least one and close to maybe three or more (vaccine) candidates.”

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, speaks about the coronavirus in the James Brady Press Briefing Room of the White House, Tuesday, April 7, 2020, in Washington. (AP Photo/Alex Brandon)

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, speaks about the coronavirus in the James Brady Press Briefing Room of the White House, Tuesday, April 7, 2020, in Washington. (AP Photo/Alex Brandon)

By mid to late fall, if the process goes well, he said there would be enough information to decide whether a vaccine is safe and effective.

“If we are in good shape and that happens, we could have a vaccine either by the end of this calendar year or in the first few months of 2021,” Fauci said. “That’s the thing that makes me feel confident that the process is really on track and that’s good news, again in the context of never being able to guarantee success, things are clearly going in the right direction.”

CORONAVIRUS IN THE US: STATE-BY-STATE BREAKDOWN

Fauci’s comments followed his warning from the day prior, when he said the fight against the spread is far from over and called the coronavirus his “worst nightmare,” an outlet reported.

“In a period of four months, it has devastated the whole world,” Fauci said during an appearance at a virtual conference held by Biotechnology Innovation Organization. “And it isn’t over yet.”

Christine Singer, vaccine research scientist at Pfizer, works on the vaccine under a laboratory fume hood. (Photo courtesy of Pfizer)

Christine Singer, vaccine research scientist at Pfizer, works on the vaccine under a laboratory fume hood. (Photo courtesy of Pfizer)

On Tuesday Fauci did express confidence that an antidote is in the works.

“I’m very heartened by the fact that the industry has stepped to the plate — very much differently than what we saw with SARS,” Fauci said. “The industry is not stupid — they figured it out. SARS had a degree of transmissibility that it burned itself out with pure public health measures. No way is that going to happen with this virus.”

He also warned against trying to implement price controls on manufacturers of vaccines, saying companies would walk away if faced with price controls, according to the New York Post.

WHO OFFICIAL WALKS BACK STATEMENT THAT ASYMPTOMATIC TRANSMISSION IS 'VERY RARE'

Of the recent developments for vaccine candidates, biotech companies like Novavax and INOVIO expect results from the Phase 1 portions of their trials by this June or July.

Meanwhile, researchers at the University of Oxford, in collaboration with AstraZeneca, hope to have the first Phase 3 data in hand this summer. In addition, Moderna is finalizing its protocol for the Phase 3 study, with an expected start in July 2020.