Scientists map immune system's response to COVID-19

Melbourne researchers have mapped immune responses from one of Australia's first novel coronavirus (COVID-19) patients, showing the body's ability to fight the virus and recover from the infection.

Researchers at the Peter Doherty Institute for Infection and Immunity (Doherty Institute) were able to test blood samples at four different time points in an otherwise healthy woman in her 40s, who presented with COVID-19 and had mild-to-moderate symptoms requiring hospital admission.

Published in Nature Medicine is a detailed report of how the patient's immune system responded to the virus. One of the authors on the paper, research fellow Dr Oanh Nguyen said this was the first time that broad immune responses to COVID-19 have been reported.

"We looked at the whole breadth of the immune response in this patient using the knowledge we have built over many years of looking at immune responses in patients hospitalized with influenza," Dr Nguyen said.

"Three days after the patient was admitted, we saw large populations of several immune cells, which are often a tell-tale sign of recovery during seasonal influenza infection, so we predicted that the patient would recover in three days, which is what happened."

Working together with the University of Melbourne Professor Katherine Kedzierska, a laboratory head at the Doherty Institute and a world-leading influenza immunology researcher, the team was able to dissect the immune response leading to successful recovery from COVID-19, which might be the secret to finding an effective vaccine.

"We showed that even though COVID-19 is caused by a new virus, in an otherwise healthy person, a robust immune response across different cell types was associated with clinical recovery, similar to what we see in influenza," Professor Kedzierska said.

Dr Thevarajan said that current estimates show more than 80 percent of COVID-19 cases are mild-to-moderate, and understanding the immune response in these mild cases is very important to research.

"We hope to now expand our work nationally and internationally to understand why some people die from COVID-19, and build further knowledge to assist in the rapid response of COVID-19 and future emerging viruses," she said.