Wuhan, China — Fears over a deadly virus outbreak in China were spreading as rapidly as the virus itself on Monday, including concern that it could come to the U.S. As of Monday there were more than 217 confirmed cases of the newly identified coronavirus, which produces pneumonia-like symptoms.

Three people have died from the illness, which has spread to at least three other Asian countries.

As CBS News correspondent Ramy Inocencio reports, the virus is fraying nerves in Wuhan, the Chinese city at the center of the outbreak. The number of people infected in China exploded over the weekend.

The airport in Wuhan has started checking people's body temperatures before they even board flights. Over the weekend U.S. officials started screening airline passengers from Wuhan as they arrive, too, though there have been no reported cases of the virus in the U.S. yet.

More than 100 officials from the Centers for Disease Control and Prevention (CDC) have been stationed at airports in San Francisco, Los Angeles and New York, screening incoming passengers from Wuhan for any sign of the deadly coronavirus.

"If it's an issue that's going to affect others, it's maybe a good choice to be cautious about it," said Sylvia Zheng as she arrived from China.

Inocencio visited the seafood and animal market in Wuhan that health officials consider the point of origin of the virus, where it first entered the human population.

Since Friday, the number of known infections in Asia has more than quadrupled, with 217 cases confirmed in China and a few others in Thailand, Japan and South Korea, which reported its first case on Monday.

A store owner argues with security guards as he attempts to enter the closed Huanan wholesale seafood market in the city of Wuhan, Hubei province, January 12, 2020. Noel Celis / Getty

Authorities say most of those cases can be traced back to the now-shuttered market in Wuhan.

The fears of a wide viral epidemic come just days before Chinese nationals are expected to make an estimated 3 billion trips — starting this weekend and going through mid-February — to celebrate their annual lunar new year. That amount of people on the move could make the virus harder to contain.

U.S. health officials are concerned the rapid spread of the virus could mimic the massive outbreak of the SARS virus (Severe Acute Respiratory Syndrome) in the early 2000's. That illness, which is related to the new strain of coronavirus, left 774 people dead in 29 countries.

A Chinese official confirmed on Monday that there have been cases of the new virus spreading from human to human, a worrying new development. State-run CCTM quoted Zhong Nanshan, a scientist at the China's National Health Commission, as saying such transmission was "affirmative," but it did not say how many cases. Chinese officials said last week that they could not rule out such human-to-human transmission.

An animal source seems the most likely primary source of this novel #coronavirus (2019-nCoV) outbreak, with some limited human-to-human transmission occurring between close contacts. pic.twitter.com/L57VUr5d3z — World Health Organization (WHO) (@WHO) January 19, 2020

The World Health Organization said on Sunday that while animal-to-human infection still appeared to be the main source of the outbreak, "some limited human-to-human transmission occurring between close contacts" had been seen.

"If the virus turns out to be readily transmissible from human to human, then we'll have a much larger problem on our hands," Dr. William Schaffner, an infectious disease specialist at the Vanderbilt University Medical Center, told CBS News.

Schaffner said public health authorities were already working on ways to fend off the epidemic.

"There are laboratories around the world already working on really good diagnostic tests, and we've already started to work on a vaccine in the event that is necessary," he said.

Inocencio was living and working in Beijing during the SARS epidemic, and he notes that the Chinese government faced major criticism for its lack of transparency as it grappled with the killer virus. Beijing authorities had withheld information from the public about the growing outbreak.

The new virus, he said, will be a test to see whether China has learned from its past to help protect its people's future.

On Monday, China's state-run media quoted Prime Minister Xi Jinping as giving his first public reaction to the outbreak, calling for it to be "resolutely contained."

Xi said "the safety of people's lives and their physical health should be given top priority," according to state TV.