A new study has found that coronavirus was able to survive inside cruise ship cabins for more than two weeks after they were vacated, including the cabins of people who tested positive but had no symptoms.

Traces of new coronavirus were found on surfaces in cruise-ship cabins for as many as 17 days after passengers left, researchers said, though it wasn’t possible to determine whether they caused any infections.

Researchers looked at the rooms of infected passengers aboard the Diamond Princess, both those who showed symptoms and those who didn’t, according to a study Monday in the Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report.

The ship, operated by Carnival Corp.’s Princess Cruises, had more than 700 coronavirus cases. It was quarantined for a time off of Yokohama, Japan, and was the largest outbreak outside of mainland China at one point.

The study results were published on the CDCs website here. One fact that needs to be pointed out is that the virus survived for this long in cabins “before disinfection procedures had been conducted.” So no one is suggesting this thing lives on for days despite a good scrubbing, only that it can linger a surprisingly long time when no cleaning has been done.

Even so, these results suggest the virus survives significantly longer on surfaces than previous research suggested. Last Tuesday the New England Journal of Medicine published a study which found the virus could survive up to three days on some hard surfaces:

The virus lives longest on plastic and steel, surviving for up to 72 hours. But the amount of viable virus decreases sharply over this time. It also does poorly on copper, surviving four hours. On cardboard, it survives up to 24 hours, which suggests packages that arrive in the mail should have only low levels of the virus — unless the delivery person has coughed or sneezed on it or has handled it with contaminated hands…

It is unclear why cardboard should be a less hospitable environment for the virus than plastic or steel, but it may be explained by the absorbency or fibrous quality of the packaging compared with the other surfaces.

Finally, even as we’re discussing how long the virus can “live” on various surfaces, there’s an interesting academic question about whether it is alive at all. Long ago I was a biology major in college and took some upper level virology classes. I still remember debates about whether or not viruses counted as living things since, much of the time, they don’t display the qualities of living organisms. Today the Washington Post has a story about how the coronavirus exists somewhere between biology and chemistry:

Outside a host, viruses are dormant. They have none of the traditional trappings of life: metabolism, motion, the ability to reproduce.

And they can last this way for quite a long time. Recent laboratory research showed that, although SARS-CoV-2 typically degrades in minutes or a few hours outside a host, some particles can remain viable — potentially infectious — on cardboard for up to 24 hours and on plastic and stainless steel for up to three days. In 2014, a virus frozen in permafrost for 30,000 years that scientists retrieved was able to infect an amoeba after being revived in the lab.

When viruses encounter a host, they use proteins on their surfaces to unlock and invade its unsuspecting cells. Then they take control of those cells’ own molecular machinery to produce and assemble the materials needed for more viruses.

“It’s switching between alive and not alive,” said Gary Whittaker, a Cornell University professor of virology. He described a virus as being somewhere “between chemistry and biology.”

We’re being threatened by something that isn’t really alive, at least not when it’s outside of our bodies. It just emphasizes the fact that this really does come down to our own behavior: Until treatments and a vaccine are ready, social distancing and proper cleaning are the only ways to stifle the threat.