Scientists are growing miniature organs to see how the coronavirus attacks the body.
These organoids based on lung, liver, kidney and intestine tissues reveal in a laboratory setting how the SARS-CoV-2 virus affects cells and causes so much damage.
According to an article in the journal Nature, they are crucially offering researchers an invaluable opportunity to experiment with medicines which could be effective against COVID-19.
Although researchers know how devastating the coronavirus can be to the body's organs, it's unclear whether some of this damage is caused by the virus directly or by the immune response it triggers.
Unlike cultured cells on a dish, organoids "resemble the true morphology of tissues," said Thomas Efferth, a cell biologist at Johannes Gutenberg University of Mainz, in Germany.
This makes them much better for studying what happens to the body, while also being much cheaper and less ethically challenging than animal studies.
But because these organoids aren't connected to each other the way organs in a body are, the research would likely eventually need to progress to animal trials.
According to the Nature article, one of the key insights organoids are providing is regarding cells in the respiratory system, from the upper airway to the lungs.
Scientists at Kyoto University in Japan have developed bronchial organoids which feature four different cell types from the bronchus - which conducts air into the lungs - and are learning which of these cells the virus attacks best.
Another study at Weill Cornell Medicine in New York City has shown the virus is particularly deadly because it causes something called a cytokine storm, a snowballing immune system response which has been seen to fill the lungs with a kind of pus made of dead cells.
But Shuibing Chen, who is a stem cell biologist at Weill Cornell Medicine, told Nature that the cause of the lung cell death is still a mystery.
"We know the cells die but we don't know how," said Dr Chen, who creates organoids not from frozen adult cells as at Kyoto University, but from pluripotent stem cells.
These stem cells are able to develop into any kind of cell type in the body, but they could also pose a challenge as the organoids grown in this way are less mature, so may not accurately represent adult tissue.
Studies on other miniature organs are ongoing, but the area of organoid research is still in its infancy.