In an era of online shopping and global shipping, some NPR listeners have written to us with this question: Am I at risk of catching the new coronavirus from a package I receive from China?

Almost certainly no, according to the Centers for Disease Control and Prevention.

"Because of poor survivability of these coronaviruses on surfaces, there is likely very low risk of spread from products or packaging that are shipped over a period of days or weeks at ambient temperatures," the CDC concludes in its Q&A.

Infectious disease specialists we spoke with were even more definitive.

"It's not going to be transported on a box," says Dr. Michael Ison of Northwestern University, who studies viral infections among transplant patients, who have weakened immune systems.

Coronaviruses are thought to mainly spread from person to person via respiratory droplets, researchers say. And, so far, the novel coronavirus seems to have spread only among people who were in close personal contact.

While there's still a lot unknown about this particular coronavirus, experts have a sense of what to expect, based on experience with previous strains that have led to outbreaks of serious illness, such as SARS and MERS.

"There is no evidence from any previous outbreak that anyone has ever gotten infected from a package," Elizabeth McGraw, director of the Center for Infectious Disease Dynamics at Pennsylvania State University, tells NPR.

McGraw says it is highly unlikely that the virus could survive for multiple days outside or inside a cardboard box, for example, that contains something an infected person had sneezed on or handled.

"What we know about these viruses is that they don't last very long on surfaces, and that's particularly the case for a very porous surface" such as cardboard, McGraw explains.

Some viruses do survive longer than others — and conditions such as temperature, humidity and surface material can influence how long a virus lives, explains Dr. Amesh Adalja, a senior scholar with the Johns Hopkins University Center for Health Security, whose work focuses on emerging infectious diseases. But many viruses outside the host fall apart within hours in the natural environment.

"Shipping conditions of most products are going to be not conducive to the virus remaining viable," Adalja told NPR's Goats and Soda team earlier this week.

In other words, Adalja concludes: "I don't think it's a real risk."

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