Initial tests to find out whether the antibodies of people who have successfully fought the virus can help others do the same have revealed that the 10 critically ill patients recovered quickly.
The treatment, known as convalescent plasma therapy (CP), was used during the 1918 Spanish flu pandemic before vaccines or antivirals were available.
It is based on the fact that the blood of people who have recovered contains strong antibodies that are trained to fight the virus.
There is currently no treatment for coronavirus and vaccines are unlikely to be available before the end of the year at the earliest.
Researchers at Jiao Tong University School of Medicine in Shanghai said results suggest that blood plasma therapy is a safe and promising treatment for severe Covid-19 patients, and called for larger trials clinics.
Sir Munir Pirmohamed, President of the British Pharmacological Society, said: “It was not a randomized trial and all of the patients also received other treatments, including antivirals such as remdesivir, which are currently being test for Covid-19. “
Sir Munir added that it was also important to remember that there are potential safety concerns around treatment, including illnesses that occur by transfusion.
He said, “Even if it’s proven effective, scalability for treating a large number of patients can become an issue. “
The pilot study, published in the journal Proceedings of the National Academy of Sciences, involved 10 patients, ages 34 to 78, who presented with severe symptoms such as shortness of breath and chest pain.
All received a transfusion of 200 ml of blood plasma, and the researchers said all clinical symptoms, which also included fever and cough, subsided within three days.
The number of white blood cells that fight disease – lymphocytes – also increased and antibody levels remained high after the CP transfusion, the researchers said.
A 42-year-old man, seriously ill and on a ventilator, breathed again for himself after two days, a result described by scientists as “remarkable”.
In the United States, the Food and Drug Administration (FDA) has approved the use of CT therapy as an experimental treatment in clinical trials and for critical patients with no other options.
In the UK, it has been reported that the NHS may begin administering therapy to hospital patients in the near future.