On Thursday, Hong Kong health officials tested two patients for the MERS virus striking at the heart of South Korea. At least one patient was confirmed not to have the deadly disease.

The patient, a woman authorities are not naming, went to a hospital after returning from South Korea with MERS-like symptoms, according to reports. Doctors immediately cordoned off the hospital and put on protective gear so they could safely interact with her.

Authorities are still waiting on results from the second potential MERS case from Wednesday, and they are also awaiting the results on an earlier patient.

However, Hong Kong’s public health officials are careful to emphasize that nearly every potential case of MERS they have encountered has come back negative when tested.

“Of the 33 suspected cases of MERS that we received … 31 have tested negative,” Leung Ting-hung, controller of Hong Kong’s Center for Health Protection, said.

Leung promised to give the public any updates about the MERS situation twice daily until the crisis ends.

Hong Kong’s markets took a plunge in response to the news about the two MERS cases still awaiting results. There are fears that panic could cause economic catastrophe.

MERS stands for Middle East respiratory syndrome. The disease attacks a victim’s lungs and breathing tubes. First contracted by humans in Saudi Arabia in 2012, MERS has a fatality rate of between 30 and 40 percent, according to United Nations health officials.

In 2014, two cases of MERS were recorded in the United States. A third tested positive for the disease, but by the time doctors tested his bloodstream, he had successfully fought off the virus. None of the victims from the United States died.

In South Korea, the most-recent nation to suffer a MERS outbreak, a tenth death due to the virus was announced earlier on Thursday. The government is keeping nearly 4,000 in quarantine, and thousands of schools and other public buildings have been shut down due to panic.

Wednesday, the South Korean president had to cancel a scheduled trip to the United States to stay home and oversee the public health response.

South Korean officials, who have been working closely with a team from the U.N.’s World Health Organization for the past week, claim the pandemic has reached its peak.

Several governments in the region around South Korea, including Hong Kong, have put warnings on travel to and from South Korea, in an attempt to limit spread of the disease.