The deadly coronavirus, which U.S. health officials have said has infected eight people in the United States as of Saturday, is one of three pathogenic coronaviruses that have been transmitted from animals into humans, and a top infectious disease doctor said that markets in China may be providing "a perfect mixing pot for this to happen."

"There are four more coronaviruses that commonly infect humans and cause the common cold. And probably all of us have been infected with those," explained Dr. Mark Mulligan, who is a senior professor in the NYU Langone Department of Medicine and director of both the NYU Langone Vaccine Center and the Division of Infectious Diseases and Immunology.

However, Severe Acute Respiratory Syndrome (SARS), Middle East Respiratory Syndrome (MERS) and the novel coronavirus are unique because they originate in animals.

"We have no prior immunity to protect us against them," Dr. Mulligan explained on Fox Nation's "Deep Dive" on Thursday. "So they're related, but they're not close enough that our previous experience with the other coronaviruses gives us protection."

The outbreak of the novel coronavirus was first reported by Chinese officials after it originated at an animal and seafood market in the city of Wuhan.

"What happens there? Is it that people touch it with their hands and then they touch their face? Is that how it spreads or is it airborne?" asked Wall Street Journal columnist Mary Anastasia O'Grady

"My understanding is that these markets have a mixture of live or dead animals that can be purchased," Dr. Mulligan said. "My understanding is these are for eating... and traditional medicine may be part of it."

"So they're consumed, but you can imagine a wild animal infected with these sorts of exotic viruses brought home killed, blood exposure and infection. This is kind of a perfect mixing pot for this to happen," he added.

"We saw this with avian influenza H5 N1, for example, in poultry markets... a similar situation," said Dr. Stephen Morse, who is a professor of epidemiology at the Columbia University Medical Center.

A U.S. CORONAVIRUS OUTBREAK MAY DEPEND ON THIS: 'WE JUST DON'T KNOW YET' SAYS INFECTIOUS DISEASE DOC

"I have a colleague who has -- probably very gross video -- of someone selling bat and they'll clip the wings off and put it in the bag so you can take it home and eat it in one of these live animal markets," he said.

"They were out there studying other bat coronaviruses. And there are a lot of them that are similar to these. But, you know, this one happens to be the one that got into humans," Dr. Morse added.

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Fox News' Vandana Rambaran contributed to this report.