Over 80% of the passengers and crew on the unnamed cruise ship who tested positive for Covid-19 were asymptomatic.
It is therefore likely that the prevalence of the virus on affected cruise ships is “considerably underestimated,” concludes the study published in the journal Thorax.
“Strategies are needed to assess and monitor all passengers to prevent community transmission after disembarkation,” said the Australian-based researchers.
Professor Alan Smyth, joint editor of the journal, said the study results could have implications for easing lock restrictions if more people than previously thought had already had the virus.
Of the 217 passengers and crew on board, 128 tested positive for the virus and of these, 104 patients – 81% – had no symptoms.
The ship left Argentina in mid-March for a 21-day Antarctic cruise along a similar route taken by explorer Sir Ernest Shackleton in the early 1900s.
He set sail after the World Health Organization (WHO) declared a global pandemic and two of the study’s authors happened to be passengers, while a third was the expedition doctor.
Passengers and crew were screened for Covid-19 symptoms, body temperatures were recorded before boarding, and no one who had recently traveled through countries with high infection rates at l ‘era, like China and South Korea, was only allowed.
The first fever recorded on board the ship occurred on the eighth day and the study authors said that by that time, all passengers were confined to their cabin and that surgical masks had been issued, while ‘complete personal protective equipment was used for all contact with feverish patients.
Eight people had to be medically evacuated from the ship and the authors said there had been one death to date.