Cruise ship study shows that 80 per cent of Covid-19 cases on board were asymptomatic
Coronavirus infection without symptoms might be more common than previously thought, according to a study of people isolated on a cruise ship during the pandemic.
More than 80 per cent of the passengers and crew on the unnamed cruise ship who tested positive for Covid-19 were asymptomatic.
The prevalence of the virus on affected cruise ships is therefore likely to be "significantly underestimated", the study published in the journal Thorax concludes.
"Strategies are needed to assess and monitor all passengers to prevent community transmission after disembarkation," the Australia-based researchers said.
Professor Alan Smyth, joint editor-in-chief of the journal, said the study's results could have implications for the easing of lockdown restrictions if more people than previously thought have already had the virus.
Of the 217 passengers and crew on board, 128 tested positive for the virus and of those, 104 patients - 81 per cent - did not have symptoms.
The ship left in mid-March from Argentina for a planned 21-day cruise of the Antarctic, along a similar route taken by explorer Sir Ernest Shackleton in the early 1900s.
It set sail after the global pandemic was declared by the World Health Organisation (WHO) and two of the study authors happened to be passengers, while a third was the expedition physician.
Passengers and crew were screened for Covid-19 symptoms, body temperatures were taken before boarding, and no-one who had recently travelled through countries with high infection rates at the time such as China and South Korea was allowed on.
The first recorded fever on board the ship was on day eight and the study authors said from that point all passengers were confined to their cabins and surgical masks were issued, while full personal protective equipment was used for any contact with any patients with a fever.
Eight people had to be medically evacuated from the ship and the authors said there had been one death to date.
