Antibodies from patients who have recovered from Covid-19 will be transferred into critically-ill patients with the disease in New York over coming days with expectation it will be an effective treatment.
Blood from people who have recovered from infection can be a rich source of antibodies; proteins made by the immune system to attack a virus after the onset of infection.
The use of antibody-rich plasma taken from the blood supply of recovered Covid-19 patients was used in a clinical trial in China. State reports suggest some patients improved within 24 hours, with reduced inflammation and viral loads, and better oxygen levels in the blood.
Mount Sinai Hospital is co-ordinating the latest effort with the New York Blood Centre, under guidance from the US Food and Drug Administration (FDA). Last week, researchers at Icahn School of Medicine based at Mount Sinai, working with scientists in Australia and Finland, were among the first to create an antibody test that detects the disease's antibodies in a person's blood.
The breakthrough was made by a team led by influenza expert Dr Florian Krammer. Their so-called recipe enabling the test known as an assay – was made available to other labs around the world so they can replicate it.
The assay is “sensitive and specific”, and allows for screening and identification of Covid-19 in human plasma/serum as soon as three days after onset of symptoms, said Dr Krammer. It also enables subsequent generation of antibodies.
Preliminary findings show humans have no natural immunity to the Sars-CoV-2 virus (its medical term), which would help explain why it spreads so quickly, he said. But once the antibody sets in humans become protected. There is no evidence people lose their immunity and become re-infected.
Known as "convalescent plasma", it has been used for decades to treat infectious diseases including those affected by the 1918 flu pandemic. Mount Sinai president Dr David Reich said it would be tried for hospitalised patients who had a moderate form of the disease and had trouble breathing but not those at advanced stages of illness.
The FDA has given permission for it to be used experimentally on an emergency basis. An email asking Mount Sinai staff members who had recovered to consider donating plasma went “a little viral” and quickly drew 2,000 responses, he confirmed.
Donors will include people who tested positive for the virus when they were ill, recovered, have had no symptoms for 14 days, now test negative and have high levels of antibodies. People who qualify will be sent to blood centres to donate plasma.
Is convalescent plasma effective?
Some experts say the treatment, though somewhat primitive, might be the best hope for combating coronavirus until more sophisticated therapies are developed, which could take months. Infusions of convalescent plasma were associated with milder symptoms and shorter hospital stays for some patients during the 2002 Sars outbreak.
Immunologist Prof Kingston Mills of Trinity College Dublin said the approach was worthwhile given it has been confirmed that those with Covid-19 are generating high levels of antibodies. In addition, higher levels are corresponding with more severe illness, while tests in animals are showing that when "rechallenged" by the virus they do not become re-infected.
A vaccine was the best chance to globally eliminate the virus, he said, but the use of “antiserum” in this way was the next best thing.
Ideally, however, it should be developed in the lab in the form of “monoclonal antibodies”, Prof Mills suggested, rather than using a serum taken from the body, which was a cocktail and not without risk – as had arisen with inadvertent transmission of Hepatitis C in the past.
