The coronavirus outbreak may be "at the brink" of a global pandemic, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, tells Axios.

What's new: Signs people are infecting each other in a more sustainable fashion in China, an uptick in confirmed cases in Japan and Singapore, and research showing people without symptoms may be able to infect each other are fueling concerns that COVID-19 will develop into a pandemic.

The state of play: The virus has killed more than 2,000 people and infected more than 75,000 others, mostly in mainland China. Five deaths and more than 800 infections have been confirmed in 28 other nations and territories.

Countries are furiously racing to contain the virus by issuing travel restrictions, imposing quarantines and isolation methods, and tracing contacts of people with known infections.

The World Health Organization has an international team in China, trying to help the country learn more about the virus, while China is testing some experimental treatments.

The latest: Based on Chinese data from more than 44,000 confirmed cases published Monday, the WHO says early indications are...

More than 80% of people who catch the infection experience mild symptoms, 14% have severe disease-like pneumonia and shortness of breath, and 5% come down with a critical disease like sepsis, multi-organ failure, and respiratory failure.

About 2% of people infected with the virus die from it — much less than other coronavirus outbreaks, SARS (~14%) and MERS (~35%).

"[T]he risk of death increases the older you are," noted the WHO, while adding researchers were trying to determine why this is the case. Young children appear not to experience as severe symptoms as older adults.

Yes, but: Fauci said there remain many unknowns — where the virus originated from, how transmissible it is, how deadly it is, and if people without symptoms are infectious.

"I would strongly suspect there are asymptomatic people transmitting [infection], but I don't think that's a major driver," Fauci said.

He adds it's too early to determine the death rate, as there is not enough data yet.

What they're saying: "There are these huge looming issues, on whether this can be contained or not. And, if it's going to spread, are we prepared to respond and mitigate it in our own country and other vulnerable places, particularly Africa?" Stephen Morrison of the Center for Strategic and International Studies told Axios last week.

Tension between economic pressures to re-open the pharmaceutical, auto and aviation factories underpinning global supply chains and markets, and the need to quarantine and control the disease could lead to a "period of stop-go, stop-go" that could worsen the situation, Morrison said.

"There's a cascade of challenges and unknowns."

What to watch: Despite efforts to prepare the American health care system for a pandemic, Morrison said the U.S. is not ready, pointing to the 2017-2018 flu season that killed at least 80,000 Americans as an example of when a sudden increase of cases "really overwhelmed the system."

"We'd be very quickly in trouble" if there was a sudden influx of ill people during a pandemic, Morrison said.

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