True coronavirus infection rate could be FIVE times higher

Eight out of ten people infected with coronavirus may never show symptoms, meaning the true infection total could be five times higher, according to an Australian study of an Antarctic cruise holiday.

A cruise ship with mostly Australian and Kiwi passengers set sail from Argentina in mid-March but quickly turned into a catastrophe as COVID-19 spread on board.

Eight passengers had to be evacuated to receive care and one died while the others were flown home.

Of the 217 passengers and crew on board, 128 tested positive for the virus, according to a study led by Professor Alvin Ing of Macquarie University and published today in the journal Thorax.

Out of those 128, a total of 104 patients, or 81 per cent, did not have any symptoms. This means there were four asymptomatic carriers for every ill passenger. 

A cruise ship with mostly Australian and Kiwi passengers set sail from Argentina in mid-March but quickly turned into a catastrophe as COVID-19 spread on board. Pictured: Coronavirus patients in Italy

Melbourne epidemiologist Ivo Mueller told the Australian Science Media Centre: ‘If the same pattern is repeated elsewhere, this means that in countries that only test symptomatic cases, the true burden of infections may be five times higher than currently reported.’

In theory, this means that Australia’s true case total could be more like 35,000 instead of the 7,150 officially recorded. 

Disease expert Professor Sanjaya Senanayake of The Australian National University said scientists are struggling to work out the true percentage of asymptomatic patients.

He said: ‘There have been varying proportions of asymptomatic cases in differing studies including about 40 per cent in study from Iceland, 18 per cent on another cruise ship, 30.8 per cent in Japanese evacuees from Wuhan and almost 80 per cent in another Chinese study. So it’s hard to know which is right.’ 

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.

‘In early March, the WHO suggested the figure of asymptomatic patients might be only one per cent, very different from the 81 per cent figure found on the cruise ship

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.

The Uruguayan government and Ministry of Health provided a ‘sanitary corridor’ for the repatriation of 112 Australian and New Zealand passengers on day 28 and for all other passengers on day 32.

Researchers from the faculty of medicine and health sciences at Macquarie University, the oncology trials unit at Sunshine Coast University Hospital and the Royal Australian College of General Practitioners believe their study to be the first instance of complete Covid-19 testing of all passengers and crew on an isolated cruise ship during the current pandemic.

More than 80 per cent of the passengers and crew who tested positive for Covid-19 were asymptomatic

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. 

He said: ‘It is difficult to find a reliable estimate of the number of Covid positive patients who have no symptoms.

‘In early March, WHO suggested the figure might be only one per cent, very different from the 81 per cent figure found on the cruise ship.

‘As countries progress out of lockdown, a high proportion of infected but asymptomatic individuals may mean that a much higher percentage of the population than expected may have been infected with Covid.

‘These individuals may have immunity to Covid. This demonstrates the urgent need for accurate seroprevalence studies to estimate the overall population infection rate across the globe.’

It remains unclear what level of immunity people develop once they have had Covid-19.

Coronavirus binds itself to the ACE2 receptor molecule in lung cells using a spike protein – the tighter it can attach itself, the less likely it is to be washed away and the sicker it makes its host

Read more at DailyMail.co.uk