The outbreak of a new coronavirus that began in Wuhan, China, has spread to more than 200 people and killed at least three in what is just “the tip of the iceberg,” according to a Boston-area infectious disease doctor.

Dr. Todd Ellerin, director of infectious diseases at South Shore Health, said with prior coronavirus outbreaks, “In some cases it was deadly so we have to take this seriously.”

Ellerin cited the 2003 outbreak of severe acute respiratory syndrome and the Middle East respiratory syndrome outbreak, which was first reported in 2012. Both are types of coronaviruses.

The virus causing the current outbreak is different from those previously identified. Initial symptoms of the “novel coronavirus” include fever, cough, tightness of the chest and shortness of breath.

The outbreak is believed to have started late last month when people picked it up at a fresh food market in Wuhan.

The head of a Chinese government expert team said Monday that human-to-human transmission has been confirmed in the outbreak, a development that raises the possibility that it could spread more quickly and widely.

“I do think this is the tip of the iceberg,” said Ellerin.

Most people have had a coronavirus at some point in their life, as it is a frequent cause of the common cold, but the so-called “novel coronavirus,” a new variation, appears to have higher mortality rates, according to Ellerin.

The virus is already spreading to other Chinese provinces, and South Korea reported its first case Monday.

Authorities in Thailand and in Japan have also already identified at least three cases, all involving recent travel from China.

Some medical workers in China have tested positive for the virus, which Ellerin said also happened during the SARS outbreak.

“That underscores the importance of meticulous or aggressive infection control or infection prevention measures,” said Ellerin.

The spread of the viral pneumonia comes as China enters its busiest travel period, when millions board trains and planes for the Lunar New Year holidays. Ellerin said that the spike in travel could spread the virus.

The Centers for Disease Control began public health screenings for the virus at San Francisco, New York and Los Angeles airports, which receive most of the travelers from Wuhan.

At least a half-dozen countries in Asia and three U.S. airports have started screening incoming airline passengers from central China as well.

While the virus doesn’t appear to pose an immediate threat to the Bay State, Ellerin said certain protocols are in place to handle such a situation.

“If we suspect one of these novel coronaviruses, the recommendation is that we immediately isolate the patient within airborne isolation,” said Ellerin.

The World Health Organization announced it would convene an Emergency Committee meeting on Wednesday to determine whether the outbreak warrants being declared a global health crisis.

Herald wire services contributed to this report.