(Reuters) - A U.S. Food and Drug Administration official on Wednesday pointed to the spread of the new coronavirus to six of the world’s seven continents as he warned of the potential for a global pandemic.

“We have to be alert to the possibility of a pandemic,” Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said in an interview after a presentation at the SVB Leerink health-care conference in New York.

“In the past week we went from having this virus on three continents to having it on six continents. ... Any time something’s going at that rate, it has to be concerning,” he said.

Marks said he is watching to see if the number of cases in Western Europe and South America surge, as has happened in Italy and South Korea.

“The more of those that occur, the more chance there is that it could evolve into a pandemic,” he said.

Marks previously told Bloomberg News, “We are on the cusp of the pandemic.”

Speaking earlier at the conference, Marks said that three-month estimates for a coronavirus vaccine to enter human trials may be too aggressive.

“We’re hoping in next quarter or two there will be a vaccine that will be ready to move” into human trials, he said.