Former FDA Commissioner Scott Gottlieb told CNBC on Friday the fast-spreading coronavirus outbreak in China is likely more contagious but less severe than the SARS epidemic that rattled markets in 2003 and slowed global economic growth.

"We probably will have some isolated outbreaks [of coronavirus in the U.S.], but that doesn't mean it'll translate to an epidemic," said Gottlieb, a physician, health advocate and Pfizer board member. He left the Food and Drug Administration in April.

The total number of coronavirus cases in China rose to over 900, with 26 deaths. The flu-like virus, which was first identified less than a month ago in the Chinese city of Wuhan in Hubei province, has also infected at least 15 people around the world, mostly in Asia. The U.S. reported one case on Tuesday, a Snohomish County, Washington, resident who was returning from China.

Gottlieb told CNBC that in comparison with SARS, this appears to be more contagious and less severe.

"But the question is, has it achieved sort of that golden point where it's contagious enough to spread rapidly but still severe enough to cause a lot of harm?" he said a "Squawk Box" interview. "We don't know that yet."

Gottlieb said there could be thousands of mild cases that will likely go undiagnosed and clear up on their own.