Unknowns of the new virus make global quarantines a struggle

A group of medical personnel prepare to meet 80 people, accompanied by medical specialists, carried by a Russian military plane at an airport outside Tyumen, Russia, Wednesday, Feb. 5, 2020. Russia has evacuated 144 people, Russians and nationals of Belarus, Ukraine and Armenia, from the epicenter of the coronavirus outbreak in Wuhan, China, on Wednesday. All evacuees will be quarantined for two weeks in a sanatorium in the Tyumen region in western Siberia, government officials said. (AP Photo/Maxim Slutsky)

FILE - In this Feb. 1, 2020, file photo, State Commission of Quality Management staff in protective gear disinfects a ground transportation area at the Pyongyang Airport in Pyongyang, North Korea. Halting the spread of a new virus that has killed hundreds in China is difficult in part because important details about the illness and how it spreads are still unknown. (AP Photo/Jon Chol Jin, File)

FILE - In this Jan. 28, 2020, file photo, a worker wearing a face mask sprays disinfectant along a path in Wuhan in central China's Hubei Province. Halting the spread of a new virus that has killed hundreds in China is difficult in part because important details about the illness and how it spreads are still unknown. (AP Photo/Arek Rataj, File)

In this Tuesday, Feb. 4, 2020, photo provided by Royal Thai Navy, Thai nationals returning from Wuhan, China, are received by medical staff wearing protective suits at U-Tapao airport in Rayong, Thailand. A plane carrying 138 Thais who have been trapped in Wuhan due to an outbreak of a new virus returned to Thailand on Tuesday. (Royal Thai Navy via AP)

FILE - In this Monday Feb. 3, 2020, file photo, cruise ship Diamond Princess is anchored off Yokohama Port in Yokohama, south of Tokyo, upon its arrival. Japanese health officials conducted massive medical checks Tuesday on all 3,700 people on the cruise ship that returned to the country after carrying one passenger who tested positive for the new coronavirus. Health authorities are scrambling to halt the spread of a new virus that has killed hundreds in China. But with important details about the illness and how it spreads still unknown, officials and medical personnel are struggling. (Kyodo News via AP)/Kyodo News via AP)

Passengers are seen on the World Dream cruise ship docked at Kai Tak cruise terminal in Hong Kong, Wednesday, Feb. 5, 2020. A Hong Kong official says more than 3,600 people on board the cruise ship that was turned away from a Taiwanese port will be quarantined until they are checked for a new virus. (AP Photo/Vincent Yu)

SEOUL, South Korea — Health authorities are scrambling to halt the spread of a new virus that has killed hundreds in China, restricting visitors from the country and confining thousands on cruise ships for extensive screening after some passengers tested positive. But with important details about the illness and how it spreads still unknown, officials and medical personnel are struggling.