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Updated: Mar 18, 2020 16:48 IST

A patient’s immune system can produce antibodies that fight mild-to-moderate cases of the coronavirus infection, reported a breakthrough study that experts say will be crucial in the development of a vaccine.

A 47-year-old woman in Melbourne with mild-to-moderate coronavirus disease, or Covid-19, produced antibodies that fought the infection and recovered in about 10 days without any medicines, the study found.

The paper, published in Nature Medicine journal on Tuesday by researchers at the Peter Doherty Institute for Infection and Immunity, was based on blood samples tested at four different time points, which detailed how a patient’s immune system responds to the virus.

To be sure, the patient was otherwise healthy, the disease was mild-to-moderate, and she was a non-smoker. She was administered intravenous fluids to prevent dehydration but not given any antibiotics, steroids or antiviral agents to treat the infection that primarily affected her lungs. She had travelled from Wuhan in China, the epicenter of the global epidemic.

“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 Katherine Kedzierska said.

“This is an incredible step forward in understanding what drives recovery of COVID-19. People can use our methods to understand the immune responses in larger COVID-19 cohorts, and also understand what’s lacking in those who have fatal outcomes.”

The study found the presence of four kinds of immune cells when the patient was sick that spurred the production of two kinds of antibodies. She was discharged to home isolation on Day 10 of contracting the disease, and her symptoms disappeared completely on Day 13. The antibodies remained in her blood from Day 7 to Day 20.

Chest scans showed the patient’s lungs clearing up after the antibodies appeared in the blood. The researchers are now working on whether the immune response will be sufficient to guard her against a future infection, Bloomberg reported.

The findings will be crucial in developing a vaccine for the coronavirus infection, which is still in its early stages of development, said experts.

Dr Irani Thevarajan, the first author of the paper, told the University of Melbourne that current estimates show more than 80 per cent of COVID-19 cases are mild-to-moderate, and understanding the immune response in these mild cases is very important research.