China agreed on Tuesday to allow international experts, expected to include Americans, to work on the ground with their scientists on the fast-spreading coronavirus.

Why it matters: Roughly 60 cases are outside mainland China, where the outbreak has infected at least 4,633 people. While China quickly provided global access to the virus genome, the epidemiology of how the virus works is hard to determine from outside China with little public data.

Details: The World Health Organization announced it will organize the international group "as soon as possible to work with Chinese counterparts on increasing understanding of the outbreak to guide global response efforts."

Health and Human Services Secretary Alex Azar said during a press conference, where he learned of WHO's announcement, that the U.S. would be "delighted" to participate.

Prior to receiving the news, Azar urged "more cooperation and transparency" from the Chinese government.

Between the lines: Researchers want to use this opportunity to study whether people can infect each other before showing symptoms, as this might change screening and quarantine practices.

Chinese health officials had said some asymptomatic people were infectious, but this has not been seen in the five current U.S. cases, all of whom traveled from Wuhan.

"Obviously, we'd have to change our operations if indeed that was a significant issue," National Center for Immunization and Respiratory Disease director Nancy Messonnier said.

In China, scientists also hope to gather data on where the virus may have originated, how fast it spreads and how severe the illnesses are. They plan to obtain specimens to build more robust diagnostics, vaccines and treatments.

The latest: While this is a "potentially very serious health threat," the risk to Americans right now remains low, Azar said. But officials are taking aggressive actions in preparation.

The CDC is expanding its entry screening to 20 locations from the five airports it designated last week, Messonnier said.

National Institute of Allergy and Infectious Diseases director Anthony Fauci said they are working on "the next generation" of diagnostics they hope will be distributed to states and possibly other nations within a few weeks. Plus, he added they are already developing a vaccine and China is testing antiviral drugs as possible treatments.

The U.S. government upped its warnings to say Americans should avoid nonessential travel to China.

Until it's determined the virus renders this method ineffective, Messonnier said the U.S. will continue its "tried and true" strategy of contact tracing — the method of reaching out and monitoring all known contacts of any infected people.

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