The most detailed scientific study yet of a coronavirus patient has produced encouraging findings about the human immune system’s ability to fight the virus and help the body recover.
Researchers at the Peter Doherty Institute for Infection and Immunity in Australia analysed blood samples from a previously healthy 47-year-old woman who contracted Covid-19 and found that her recovery was due to an unexpectedly strong immune response.
The woman, whose blood was tested at four different points during the course of the disease, had travelled to Melbourne from Wuhan in China where Covid-19 originated.
She was admitted to hospital with typical symptoms of moderate Covid-19, which had begun four days earlier: lethargy, sore throat, dry cough, chest pain, shortness of breath and fever.
“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,” said Professor Katherine Kedzierska of the Doherty Institute.
Her chest was clear 10 days after she was admitted to hospital, she was discharged on day 11, and all symptoms had disappeared by day 13. Antibodies against the virus that causes Covid-19 continued to increase until the study ended on day 20.
A scientific paper on the case was published in Nature Medicine. Oanh Nguyen, another member of the team, said it was the first report of broad immune responses to Covid-19.
The virus’s death toll nonetheless continues to rise. The number of people confirmed to have died as a result of it has now surpassed 11,200 globally, with most of the victims elderly or sufferers of underlying health conditions.
The most important scientific uncertainty about Covid-19 is the strength and longevity of the human immune response — and in particular whether it is sufficient to build up lasting immunity in people who have been infected, or those who receive as-yet-undeveloped vaccines against the virus.
This study shows a powerful initial response, but no Covid-19 patients have recovered for long enough to judge its longevity.
“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 hospitalised 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.”
The unnamed woman received intravenous fluids to keep her hydrated but received no antibiotics, steroids or antiviral drugs, and she did not need oxygenation on a ventilator.
“This is an incredible step forward in understanding what drives recovery from 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,” said Prof Kedzierska.
There was also encouraging news about the immune response to Covid-19 in a different study by scientists at Peking Union Medical College in China, who infected macaques with the virus. They found that the monkeys produced enough antibodies to resist further infection.
Although caution is needed in extending the results of animal experiments to people, the Chinese researchers suggested that human patients would also respond strongly enough to prevent reinfection and make it possible to develop effective vaccines.
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