South Korea's health authorities said Wednesday they have not diagnosed new additional cases of the new coronavirus in the country but are monitoring 28 other potential cases amid heightened quarantine rules.

So far, the country has confirmed four cases of the novel virus, with the latest one reported Monday.

According to the Korea Centers for Disease Control and Prevention, 187 people have experienced signs of the new virus strain since Jan. 3, and 155 have tested negative and been released from observation and isolation.

Of the four confirmed cases, the first was reported Jan. 20, with the others coming Friday, Sunday and Monday. Authorities said they are keeping close tabs on the 387 citizens who may have come in contact with those infected.

The third and fourth patients were asymptomatic upon arrival here from the Chinese city of Wuhan, the epicenter of the fast-spreading virus, raising concerns they may have spread it to others unknowingly.

The third person patient is known to have been in contact with

95 people, with the fourth confirmed case having come in contact with 172 people.

Common symptoms of the coronavirus, thought to have originated in Wuhan, central China, include fever, sore throat and breathing difficulties, with more acute cases involving chills and muscle pain.

South Korea has already raised the country's infectious disease alert level one notch from "yellow" to "orange," the third highest.

The country, moreover, is currently engaged in screening about

3,000 people who have arrived in the country from Wuhan after Jan. 13.

Park Hye-kyung, the director of the KCDC's public health emergency and bioterrorism department, said officials are contacting everyone on the list individually and checking up on their health.

In regards to the potential for spreading the new virus, she could not make any prediction at present, especially since South Korea's proximity to China means the situation will only be resolved if the outbreaks in the originating country are contained.

"Domestically, the country could technically declare an end of the health crisis only after 28 days have gone by without a patient being discovered," the health expert said. The period reflects the 14-day-long known incubation period of the coronavirus, plus another two weeks for extra margin of safety.

The whole of China has been categorized as a "coronavirus risk area," and Seoul has strongly advised its citizens not to visit the central Chinese city.

Airports across South Korea have set up checkpoints to screen passengers from China and other countries for signs of illness, with local authorities accelerating quarantine efforts to contain the virus as people return from visiting relatives and from foreign travels.

China had confirmed 132 deaths and 5,974 people infected with the virus as of early Wednesday.

The total number of infected cases worldwide has reached 6,052.

Outside China, Japan, Taiwan, Thailand, Vietnam, Singapore, Malaysia, Nepal, Macao, Hong Kong, United Arab Emirates, France, Germany, Australia, Canada and the United States have confirmed cases of the new virus. (Yonhap)