Researchers have made the startling discovery that cabins aboard the Diamond Princess cruise ship harboured the novel coronavirus for up to 17 days after passengers had left the ship in Yokohama, Japan.
The Princess Cruises ship, carrying 3 700 passengers and crew, was quarantined on 5 February by Japanese officials in the port of Yokohama after Covid-19 was detected.
The vessel became a coronavirus hotspot in its own right and more than 700 other passengers and crew were infected with Covid-19, leading to 10 fatalities.
Now research assessed by the US Centres for Disease Control (CDC) has revealed that surfaces in cabins occupied by infected passengers, who showed symptoms or were asymptomatic, continued to harbour the virus responsible “for up to 17 days after cabins were vacated on the Diamond Princess”.
The virus was identified before disinfection procedures had been conducted.
The findings showed that the virus survived on surfaces for far longer than was originally believed.
Previous analysis found that the virus remained on plastic and stainless steel for up to three days, although levels fell dramatically over time.
It was less stable on copper, where no viable virus was found after four hours, and cardboard, which was clean after 24 hours, according to the report in the New England Journal of Medicine.
The CDC said researchers couldn’t “determine whether transmission occurred from contaminated surfaces” and that further study of Covid-19′s spread through touching surfaces on cruise ships was warranted.
They also emphasised that cruise ships "are often settings for outbreaks of infectious diseases" and should be avoided during the pandemic.
As of 17 March, there were at least 25 cruise ship voyages which had confirmed Covid-19 cases that were detected either during the cruise or after it had ended, according to the CDC.
“Cruise ships bring diverse populations into proximity for many days, facilitating transmission of respiratory illnesses,” the CDC said.
“Outbreaks of Covid-19 on cruise ships pose a risk for rapid spread of the disease beyond the voyage.
“Aggressive efforts are required to contain spread. All persons should defer all cruise travel worldwide during the Covid-19 pandemic.”