NOEL KING, HOST:
There's new evidence that the coronavirus can live on some surfaces for up to two to three days. Which surfaces? Here's NPR's Allison Aubrey.
ALLISON AUBREY, BYLINE: The new study looked at the novel coronavirus in a laboratory setting and found the virus can survive up to 72 hours on stainless steel and plastic surfaces and on cardboard up to 24 hours. Jamie Lloyd-Smith of UCLA is one of the authors.
JAMIE LLOYD-SMITH: We're talking about potentially days of infectivity on some of these surfaces.
AUBREY: The study gives a range of possible survival times, but keep in mind, in a lab, all the conditions are stable. In the real world. Factors such as sunlight can kill off viruses faster. Lloyd-Smith collaborated with scientists at the Rocky Mountain Laboratories, a federal lab, to do a series of experiments. They picked up bits of virus from surfaces that had been contaminated. They then put the virus in cell cultures to test whether it was still infectious. They also tested how long the virus remained viable in the air.
LLOYD-SMITH: What these experiments show is that the virus can remain viable floating in the air for some number of hours. The experiments went out to three hours, and, you know, there were still viable viruses present.
AUBREY: Lloyd-Smith says this experiment definitely does not prove that people have been infected this way by particles of virus that float in the air, what scientists call aerosolized transmission. He says what remains unknown is what dose is needed to infect someone.
LLOYD-SMITH: There are a lot of things we don't know, so we do not yet know how many viral particles need to get into somebody's airway to initiate an infection.
AUBREY: In all these tests, the new coronavirus tends to behave a lot like an older one, SARS, that led to an outbreak in 2003. In fact, the new study shows both viruses remain viable about the same amount of time. But that leads to an important question - why has this virus spread much more widely? Lloyd-Smith says there could be multiple reasons.
LLOYD-SMITH: Things like the apparent ability of this novel virus to be transmitted and shed by people who aren't showing severe symptoms or may not be showing symptoms at all, which makes this virus much harder to contain.
AUBREY: And given all this, the advice that we've been hearing for weeks now remains the same - wash your hands. That's still the best way to protect yourself. Allison Aubrey, NPR News. Transcript provided by NPR, Copyright NPR.