While China makes up 98% of confirmed coronavirus infections, several other countries have reported the illness, including the United States.

There have been four cases in the U.S., as the Los Angeles County Department of Public Health said Sunday that a patient was diagnosed who had traveled to Wuhan, China. The patient has been hospitalized but no other information about the patient's condition has been released.

The Centers for Disease Control and Prevention confirmed a third case of the coronavirus in the U.S. this weekend, with a patient in Orange County, California. The patient was also a traveler who had returned from Wuhan, which has been the epicenter of the coronavirus outbreak since it began in January.

According to a statement from the O.C. Health Care Agency, the third patient is in good condition and is being kept in isolation to lower the risk of the virus spreading.

“There is no evidence that person-to-person transmission has occurred in Orange County,” the statement read. “The current risk of local transmission remains low.”

The first two cases confirmed in the U.S. were in Chicago and Everett, Washington. Both patients are reportedly being kept at hospitals for treatment and are said to be recovering well.

In China, the coronavirus has claimed over 50 lives and current estimates put its reach at over 2,000 cases. Chinese health minister Ma Xiaowei claimed on Sunday that the virus has been found to spread between people before symptoms begin to show. This makes the treatment and containment of the disease much more difficult, as patients may be spreading it for weeks before they are diagnosable.

CNN's senior medical correspondent Elizabeth Cohen said on Sunday that U.S. health officials were surprised by the Chinese minister's claims. "If indeed he is right — and it's an 'if' — this virus can be spread before you even get sick ... that is a big deal."

U.S. officials, meanwhile, stated on Friday that the chances are low of the virus spreading before symptoms show. The incubation period for coronavirus has been found to be roughly two weeks.

“Based on what we know now about this virus, our concern for transmission before symptoms develop is low, so that is reassuring," Dr. Jennifer Layden of the Illinois Department of Health said on Friday.