Coronavirus RNA detected on cruise ship 17 days after passengers left: CDC report

Traces of the novel coronavirus were detected on a number of surfaces in cabins aboard the Diamond Princess cruise ship up to 17 days after passengers disembarked, a new report from the U.S. Centers for Disease Control and Prevention (CDC) says.

The CDC report, released on Monday, said RNA from the virus was found “on a variety of surfaces in cabins of both symptomatic and asymptomatic infected passengers up to 17 days after cabins were vacated” but before disinfection procedures were conducted.

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The report’s authors cautioned, though, that the data “cannot be used to determine whether transmission occurred from contaminated surfaces.”

The CDC says further study of COVID-19 transmission from inanimate objects “is warranted.”

What is RNA and what does this mean?

According to Alon Vaisman, an infection control physician at the University of Toronto, RNA is the “the basic building block of the genetic code for the virus.”

He said RNA being found on a surface does not necessarily mean that the virus is alive, just that the virus was there at some point.

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“We don’t know if it’s live virus or not, all that we know is that it’s genetic material,” he said.

Vaisman said that based on other studies, it’s “unlikely” that this RNA would be from live virus, but that this information was “not explicitly said” in the CDC report.

In an email to Global News, Jason Kindrachuk, an assistant professor and Canada Research Chair in emerging viruses at the University of Manitoba, said pieces of viral RNA can remain on surfaces for extended periods of time, but “this does not reflect infectious virus.”

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What’s more, Vaisman said the report didn’t clarify if the RNA that was detected signals transmissible virus.

“So if you had touched this leftover viral material — again, not knowing whether the virus is actually alive or dead — can you pick up the virus?” he said. “That seems unlikely, but that wasn’t confirmed in this piece of information, so we don’t know that much at all.”

Jason Tetro, a microbiologist and author of The Germ Code, told Global News that if it was only RNA that was found, that means there is no chance of life “whatsoever.”

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As we know, the longest a coronavirus can last on a surface is nine days in a laboratory — you can’t get it to last longer than that,” he said. “So this identification does not have any impact on transmission on the risk for humans, it just simply means that at one time or another, the virus happened to be on their ship.”

Vaisman said it is also important to note that the RNA was detected aboard the Diamond Princess before it was disinfected.

A study published last week in the New England Journal of Medicine found that the novel coronavirus can remain “viable and infectious” in droplets in the air for hours and on surfaces up to days.

Scientists from the National Institute of Allergy and Infectious Diseases (NIAID), part of the U.S. National Institutes of Health, attempted to mimic the virus deposited from an infected person onto everyday surfaces in a household or hospital setting, such as through coughing or touching objects.

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The tests show that when the virus is carried by the droplets released when someone coughs or sneezes, it remains viable, or able to still infect people, in aerosols for at least three hours.

On plastic and stainless steel, viable virus could be detected after three days. On cardboard, the virus was not viable after 24 hours. On copper, it took four hours for the virus to become inactivated.

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However, Tetro said the NIAID study was conducted in a laboratory, in a controlled environment.

“When you look at real-life situations, the virus will have an exponential decay over the first few hours, no matter what surface it happens to be on,” he said. “The real risk only occurs over the course of a half day, and then after that, it’s not so much of a risk.”

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He said even though you may still be able to find traces of the virus for up to 48 hours, it is in such a low concentration that it may not have “any ability to infect another person.”

Does this change anything?

Overall, Vaisman said the CDC report does not change the way public health officials are reacting to the COVID-19 outbreak, but it does show a need for further testing to look at how long the virus could survive in public spaces over a long period of time.

Kindrachuk echoed Vaisman’s remarks, saying the report provides information on how health officials can screen for virus in the community when performing epidemiological investigations but that “the same principles for coronaviruses, and SARS-CoV-2, and disinfection or hygiene still apply.”

-With files from Reuters

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