As the number of global cases of Covid-19 soars above 13 million, scientists are learning ever more about what the virus does to those it infects.
But some of the findings are revealing new and alarming aspects of this insidious disease. Here, The National gives a breakdown of the latest scientific thinking.
Survivors may face permanent damage to their heart and lungs
New research suggests that patients who survive infection still suffer severe damage to their heart and lungs.
An international study of more than 1,200 patients hospitalised with Covid-19 has found that almost half had abnormalities in how their hearts pumped blood around their bodies – despite having no previous history of heart disease.
Around 1 in 8 had severe difficulties, raising fears of permanent damage needing long-term treatment.
“Damage to the heart is known to occur in severe flu, but we were surprised to see so many patients with damage to their heart with Covid-19 and so many patients with severe dysfunction”, said Professor Marc Dweck of the University of Edinburgh, lead author of the British Heart Foundation-funded study.
“We now need to understand the exact mechanism of this damage, whether it is reversible and what the long-term consequences of Covid-19 infection are.”
There is also mounting evidence that the virus causes permanent damage to the lungs. According to New Scientist, reports suggest as many as 1 in 5 patients may be affected.
Again, other viruses have been linked to permanent lung damage, but doctors have been shocked by the prevalence of cases now emerging.
Asymptomatic people can also suffer organ damage
Even those who display none of the symptoms of infection can still incur serious health effects, according to new research.
A study of passengers aboard a cruise ship which experienced an outbreak of Covid-19 in February showed signs of lung damage among asymptomatic patients who had showed no signs of being infected, despite testing positive for the virus.
Similar results have been found in another as-yet unpublished study by doctors in South Korea.
Infection with the virus may not lead to permanent immunity
The belief that infection with the coronavirus leads to life-long protection has led to so-called "Covid parties" where people deliberately try to get infected.
Even among young people - widely thought to be at low risk of serious illness - this has already proved a fatally flawed belief.
Evidence is now emerging that exposure to the virus may only provide a brief window of immunity. A study by researchers in China, published in the journal Nature Medicine, showed that levels of disease-fighting antibodies decline within weeks of initial exposure to the Covid-19 virus.
Among people who never showed symptoms, the levels fell back to those prior to infection in just two months.
Similar results have been found by researchers in the UK. In an as-yet unpublished study of more than 90 patients and healthcare workers at two London hospitals, fewer than 1 in 5 had maintained their level of disease-fighting antibodies three months after being infected by the virus. For some, it had vanished.
Concerns emerge over effectiveness of a vaccine
All these findings suggests that even if a vaccine is developed – which is by no means guaranteed – it may not give the hoped-for “one shot protection” against Covid-19.
Similarly short-lived protection has been noted with other coronaviruses – but most of these cause only mild disease.
“With the more serious, sometimes fatal, outcomes of SARS-COV2, this is troubling indeed”, said Professor Stephen Griffin of the University of Leeds.
“Vaccines in development will either need to generate stronger and longer lasting protection compared to natural infection, or they may need to be given regularly”.
Robert Matthews is Visiting Professor of Science at Aston University, Birmingham, UK