Moderna, a biotech company based in Cambridge, Mass., announced Tuesday that their experimental coronavirus vaccine succeeded its Phase 1 trial. An immune response was triggered in all 45 people who received the vaccine in the trial, researchers reported.

But medical ethicist Arthur Caplan told Boston Public Radio on Wednesday that you should "not be as excited as Donald Trump, not as excited as the stock market, and not as excited as a lot of the news reports," regarding this success. That's because although the Phase 1 study had good results, the next phases will be prolonged and much more challenging, Caplan said.

"This is a study that's called a Phase 1 study, a safety study primarily," he said. "It had good results, people built a little immunity, however it's probably many, many, many months away to recruit and complete the key study, which is a randomized trial on 30,000 people."

Art Caplan is the Drs. William F and Virginia Connolly Mitty Chair, and director of the Division of Medical Ethics at the NYU Grossman School of Medicine.