Researchers have made the startling discovery that traces of the coronavirus lingered around for more than two weeks on the Diamond Princess after passengers had left the one-time quarantined ship.

Traces of new coronavirus were found on surfaces in cabins where people who were infected with the virus had stayed for up to 17 days after they had left, according to a study released Monday along with the Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report.

The passengers had showed symptoms or were asymptomatic, researchers of the CDC study say.

Traces of the coronavirus were found on the Diamond Princess cruise ship, which had more than 700 confirmed cases of the deadly flu-like illness, after it was vacated, researchers say. The vessel is seen docked in Yokohama Port near Tokyo in February

The traces were found on surfaces in cabins where people who were infected with the virus had stayed, for up to 17 days after they had left. Passengers are pictured on deck just before they left the vessel in February

The passengers whose rooms were found to have traces of the coronavirus had showed symptoms or were asymptomatic. Health officials are pictured suiting up in protective gear to treat passengers from the Diamond Princess

It was not possible to determine whether the new traces caused any infections, Bloomberg reports.

Hundreds of thousands of people have been diagnosed around the world with the coronavirus since the global pandemic began in Wuhan, China, in December.

There have been more than 43,000 confirmed cases in the US of the infection, also known as COVID-19, which has been blamed for 553 known deaths.

More than 46,000 people tested positive for coronavirus by Monday night, and close to 600 were dead

How the number of coronavirus infections have escalated over time

How the number of deaths related to coronavirus infection have risen over time

An earlier study found that the virus was able to stay viable on plastic and stainless steel for as many as three days, although levels fell dramatically over time.

The virus was less stable on copper, where no viable trace of the virus was found after 4 hours.

It also was not as stable on cardboard, which showed no trace of the virus after 24 hours, according to the report in the New England Journal of Medicine.

The latest study from the CDC looked at rooms that were not yet cleaned. Cleaning, researchers have confirmed, is a highly effective way of killing the virus.

The CDC also said that the spread of infection aboard the Diamond Princess happened before the ship went into quarantine. Infections among crew members rose after.

On the vessel’s sister ship, the Grand Princess, members of the crew are believed to have contracted the virus and then passed it on to passengers, according to the study.