Australian study raises questions about how many have had Covid-19 with no symptoms

An Australian respiratory physician stuck on a Covid-19-plagued cruise ship has released research which found 81 per cent of virus-positive passengers didn’t display symptoms.

The study is now raising questions about how many people have had the virus without knowing.

The ship, stranded on a trip to Antarctica, allowed Macquarie University researcher Professor Alvin Ing to track positive Covid-19 tests and symptoms in real time. 

“[I was] completely blown away by how many were positive, but also how many were positive and asymptomatic,” Mr Ing said. 

“The lesson we learnt is that we probably should be testing a larger cohort if we have the resources to do so.” 

When the ship left Argentina for Antarctica in March with 112 Australians and Kiwis, it was believed to be Covid-19-free. However, a passenger developed a fever eight days into the trip. Three days later, 12 people had fevers.

Testing by Uruguay medical professionals found 128 positive cases of the virus. However, 104 people displayed no symptoms. 

Mr Ing’s study also raises questions about natural immunity. Mr Ing never tested positive for Covid-19 and didn’t develop antibodies even though he was sharing a cabin with his brother-in-law who had the virus.