A general view of the Centers for Disease Control and Prevention (CDC) headquarters in Atlanta, Georgia. Image Credit: REUTERS

An evacuee from China who had been evaluated for coronavirus was briefly released from a San Diego hospital before further testing alerted authorities that the person was infected, health officials say.

The person was among four cleared Sunday for discharge from UC San Diego Health after testing negative for the virus, the health system said in a statement. The four returned to quarantine at a nearby air station. But on Monday morning, more testing that came back positive led one evacuee to return to the hospital for "observation and isolation," the statement said.

The patient was one of hundreds flown back to the United States from Wuhan, China, the epicenter of a now-global outbreak that has taken more than 1,000 lives. While the virus's toll remains concentrated in China, where officials report more than 42,000 cases, governments around the world have been scrambling to get their citizens out of the illness's way and watch them closely for signs of infection on return.


UC San Diego Health spokeswoman Yadira Galindo said in an email that the patient left the hospital "the same way they arrived with all precautions taken." The person wore a mask and was escorted by federal officials who also had "protection," she added.

"The patient did not interact with the environment after leaving the hospital room," Galindo said.

Americans returning from Wuhan undergo 14 days of quarantine meant to prevent them from spreading coronavirus in the community. The first group put under quarantine, at California's March Air Reserve Base, is set for release Tuesday.

This is an accurate test. A negative test most likely means a person is not infected. However, it may mean that an infection has not developed enough to be detected by the test.

- Nancy Messonnier, Heads of coronavirus response at the CDC

But health authorities have cautioned that a negative test result from the Centers for Disease Control (CDC) and Prevention's laboratory does not necessarily mean someone will not get the virus.

"This is an accurate test," said Nancy Messonnier, who heads the coronavirus response at the CDC, in a briefing last week. "A negative test most likely means a person is not infected. However, it may mean that an infection has not developed enough to be detected by the test."

Messonnier told reporters that the testing is generally not meant to drive "individual decision-making" but rather to help public health officials understand the virus. If someone starts showing symptoms, though, she said, the testing may become more important on an individual basis.

The CDC did not immediately return inquiries Tuesday morning, and UC San Diego Health representatives did not clarify why the released patient's test results changed to positive. Exactly how long the evacuee was out of the hospital is not clear.

The patient will remain in the hospital until cleared by the CDC, which had approved the earlier discharge, according to UC San Diego Health.

The CDC on Monday confirmed a 13th coronavirus infection in the United States, saying in a statement that it was investigating the Wuhan evacuee's contacts and working "to assess if those contacts had high-risk exposures."

A new patient taken Monday to UC San Diego Health from the Marine Corps Air Station Miramar will stay in the hospital until the CDC confirms test results, officials say. That person's arrival raises the total number hospitalized after quarantine at Miramar to eight, according to the Los Angeles Times.

Both that patient and the briefly released evacuee "are doing well and have minimal symptoms," UC San Diego Health said.