Passive immunity

Blood from people who recover from coronavirus could provide a treatment

Plasma is being studied as a way to fight off the virus

A transmission electron micrograph of SARS-CoV-2 virus particles, isolated from a patient. (NIAID/National Institutes of Health Handout/EPA-EFE/Shutterstock)


Carolyn Y. Johnson and 

Ben Guarino 

March 28, 2020 at 12:00 a.m. GMT+5:30


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An old idea for fighting infections — an approach most physicians know about only from medical lore — is being revived as people wait for drugs and vaccines to thwart the novel coronavirus. If it works, the blood plasma of people who have recovered from covid-19 would be used to protect health-care workers and help sick people get well.

The possible therapy is based on a medical concept called “passive immunity.” People who recover from an infection develop antibodies that circulate in the blood and can neutralize the pathogen. Infusions of plasma — the clear liquid that remains when blood cells are removed — may increase people’s disease-fighting response to the virus, giving their immune systems an important boost. The approach has been used against polio, measles, mumps and flu.

“The recovered people could have in their blood something that could be very useful,” said Arturo Casadevall, chair of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health. “The history is this has been used in 120 years in medicine, and it’s well-known.”


Casadevall is hopeful the treatment, called “convalescent plasma,” could provide short-term relief to a medical system that faces a surge of patients, with no approved drugs or vaccines. But he and colleagues face regulatory, logistical and scientific challenges to set up a process that will ultimately be limited in how many people it can treat. Researchers must collect blood plasma from people after they’ve recovered, then test it to determine if it is likely to be potent against the disease and deliver it to patients.

The coronavirus outbreak has led to a blood shortage. The American Red Cross is pleading for help.

Infectious disease specialists are sharing information through grass-roots networks, helping each other with clinical trial designs and ideas on how to screen plasma for virus-fighting antibodies.

New York Gov. Andrew M. Cuomo (D) announced his state would begin trying the treatment in patients stricken with covid-19, the disease caused by the coronavirus. The Food and Drug Administration announced Tuesday it was helping facilitate access to the experimental treatment, while underscoring the need to establish safety and effectiveness. Mount Sinai Health System in New York announced this week that it plans to begin transfers of antibody-rich plasma from recovered patients to people who are severely ill.


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“We get really hung up on always trying the newest, latest, greatest thing. And sometimes the classics are good, too, and they tend to be ignored,” said Jeffrey P. Henderson, an infectious disease specialist at Washington University in St. Louis, who is working on the project.

First, experts must develop tests to measure the levels of antibodies, and then use those to identify donors whose plasma is rich in antibodies that could help others battle the illness. Then, they have to deliver the plasma to patients — most likely in clinical trials designed to measure whether it works. The plasma must be safe and disease-free, not only from other blood-borne pathogens but also from the novel coronavirus.

Plasma could be used to treat people who are sick and to prevent illness in health-care workers, Casadevall said, especially those at greatest risk for developing the illness because of repeated exposure.


“Convalescent plasma has a real role — this has been going on for over 100 years. We know this stuff works,” said Wayne A. Marasco, an infectious disease physician at Dana-Farber Cancer Institute in Boston. “If you do this right and harvest plasma from someone who has undergone infection, you can get protective antibodies that can be infused in other people.”

Access to the therapy is likely to vary. Many hospitals are racing to set up clinical trials that would be open to patients who meet specific criteria. The FDA has also created a track for “emergency use” — a way for people with serious or immediately life-threatening illness to gain access to the treatment. But many logistical questions need to be solved, including the question of who will pay for the experimental treatment.

On Friday, Bloomberg Philanthropies and the state of Maryland announced they would jointly provide $4 million to support the effort.

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