A synthetic brain has helped to reveal why people born with Down syndrome are more vulnerable to COVID-19.
Researchers from the University of Queensland developed the synthetic organoid, a mini organ, grown from human stem cells, used to study disease.
They found certain parts of the choroid plexus - a vital line of defence against viruses in the brain - is underdeveloped in people with Down syndrome.
University of Queensland's Institute for Bioengineering and Nanotechnology senior research fellow Mohammed Shaker said if someone with Down syndrome contracts COVID-19 it is easier for the virus to enter the brain.
"People with Down syndrome have 10 times higher risk of severe illness and death if they contract COVID-19," he told AAP.
The researchers then used the brain organoid they developed to screen for drug therapies, which may compensate for the vulnerability.
Dr Shaker said a number of therapies were found, including a few already approved by the US Food and Drug Administration.
"I really hope our findings will lead to better protection and treatment for those most at risk," he said.
The brain organoid the researchers developed is the first to represent two functional brain domains.
Dr Shaker said the model had implications for further studies on diseases which affect the brain, including the mosquito-borne Zika virus.
"Our organoid model can be used to study a wide range of neurological conditions, paving the way for new treatments and improving our understanding of brain diseases," he said.
"It's not limited to Down syndrome and COVID."
The research was published in the journal Science Advances.