FLASHBACK: MSNBC medical expert claimed Trump’s vaccine promise was ‘impossible’

Redlener assured viewers that the COVID-19 vaccine would not in fact be ready before the new year, contradicting the President's claim that it would be.

MSNBC host Brian Williams asked, "The American people were promised, the promised was held out that we would have a vaccine by the end of this year. Is that possible in your view?"

"No Brian. You know it's another day of POTUS in wonderland here," Redlener replied.

"It is preposterous to make that statement and also to mislead the American people about what's possible and what's not possible. We could have a vaccine in two months if we wanted to forego the absolutely critical phase of long human testing to make sure that the vaccine works, and most importantly that it's safe," he continued.

"It is impossible to get that done by the end of the year," Redlener added.

The FDA approved the Pfizer COVID-19 vaccine Thursday. A vaccine from Moderna is expected to be approved for emergency use by the FDA on Thursday Distribution of the vaccine across the country began over the weekend.

There are expected to be enough doses of the Pfizer vaccine to immunize 20 million people by the end of the year, according to Health and Human Services Secretary Alex Azar.

MSNBC also published a written fact check of the President's assertion that the vaccine would be ready in 2020, quoting experts that said he would need a "miracle" to be correct.

"I think it's possible you could see a vaccine in people's arms next year — by the middle or end of next year. But this is unprecedented, so it's hard to predict," Dr. Paul Offit said, who is a professor at the Perelman School of Medicine at the University of Pennsylvania and the director of the Vaccine Education Center at Children's Hospital of Philadelphia.

Professor at Emory University and the associate director of the Emory Vaccine Center, Dr. Walter Orenstein, said that producing a vaccine in under a year would be "miracle."

Moderna was one of six companies that were part of the Trump administration's Operation Warp Speed, in which the government settled on three technologies to investigate to create a vaccine, and then enlisted six companies to do that research. Each technology was given to two companies to give each method the best chance of success.