Delta Airlines, American Airlines and United Arlines suspended all of their flights to China as coronavirus cases in the country top 9,600.

Meanwhile, the Centers for Disease Control and Prevention ordered a federal quarantine order for all 195 passengers who were repatriated from Wuhan, China, and are currently voluntarily quarantined at a base in California. The quarantine, the first order of its kind in 50 years, will last for 14 days from when the plane left Wuhan, health officials said at a news conference Friday.

Delta will temporarily suspend flights starting Feb. 6 through April 30, due to “ongoing concerns related to the coronavirus,” the company said in a statement.

Until Feb. 5, flights will continue to operate, in order to ensure that passengers who want to leave China can do so. The final China-bound flight is scheduled to depart Feb. 3.

American Airlines canceled all of its China flights shortly after Delta made its flight suspension announcement. American said flight suspensions were effectively immediately would run through March 27.

United Airlines followed suit later in the day. Flight suspensions will begin Feb. 6. and run through March 28 for United.

Other airlines around the world have similarly suspended some routes to China, including British Airways, Air Seoul, Lion Air, Lufthansa Group, Cathay Pacific, Finnair, Air Asia, Air India, Air Canada, All Nippon Airways, Asiana Airlines and Korean Air.

Delta’s sweeping cancellations come hours after the State Department issued a warning to Americans not to travel to China because of coronavirus. Anyone currently in China should “consider departing,” according to the State Department, and non-essential government workers should defer travel to the country.

Concerns about the virus and its transmission continue, with 2,000 new cases of coronavirus reported in China over the last 24 hours. Worldwide, nearly 9,800 people have been sickened, outstripping the 8,098 cases reported during the 2003 SARS outbreak. Despite the accelerating case count, however, the new coronavirus appears to be less fatal than SARS. The World Health Organization estimates that 20% of cases of the new coronavirus are considered to be severe and 2% are fatal. In comparison, the SARS’ fatality rate was roughly 10%.

Compared to SARS, which killed 774 people, 231 people have died in the new coronavirus outbreak. All of those deaths have been in China.

It’s also expected that the fatality rate for the new coronavirus will decline as more cases continue to be reported, because individuals who are the sickest tend to be the first to seek medical treatment.

Many questions remain about how the virus is transmitted and how infectious it is.

Several countries outside of China, including the United States, have reported instances of human-to-human transmission of the virus. For now, the World Health Organization believes that the disease’s incubation period is between two and 14 days, a wide range.

It’s not known whether patients are infectious before they show signs of symptoms.

Doctors in Germany published a letter in the New England Journal of Medicine Jan. 30, reporting the case of German patient who contracted coronavirus from his business partner, who was visiting from China and who did not have symptoms during the course of her stay.

The Centers for Disease Control and Prevention maintains that there isn’t enough data yet to determine whether the virus can be transmitted before a patient who is infected develops symptoms.

Faced with so much uncertainty, countries are scrambling to react. In Italy, a cruise ship carrying 7,000 people was held in port for hours on Jan. 30, after a passenger came down with flu-like symptoms. It turned out to be a false alarm and Italian health officials diagnosed the sick passenger with the common flu.

“Individuals and governments are trying to make decisions based on speculation and minimal information,” said Dr. Irwin Redlener, director the national center for disaster preparedness at Columbia University.

“We’re trying to sort of grope our way through this,” he told ABC News. “There’s no playbook here.”

Without knowing how infectious the new coronavirus is, it’s difficult to assess whether countries’ aggressive policies are extreme or rational, Redlener explained.

If the virus turns out to be highly contagious, “that could lead to a number of decisions that could seem pretty draconian.”

ABC News’ Mina Kaji contributed to this report.