https://www.sciencemag.org/news/2020/05/can-plasma-covid-19-survivors-help-save-othersConvalescent serum could also help prevent infection in those at high risk. In a trial coordinated by Johns Hopkins, 150 health care workers exposed to COVID-19 while not wearing proper protection will receive either convalescent serum or serum collected last year. Researchers will compare how many people in each group develop disease.
If convalescent plasma is shown to work, much more of it may be needed, and supply could become a challenge, Bhadelia says. One plasma donation—the volume depends on the donor's weight but it's usually between 690 and 880 milliliters in the United States—is enough for just one or two patients, and the donor's blood type needs to match the recipient's. But recovered patients might be able to donate plasma multiple times. In New York City, there is now more than enough to go around, in part because thousands of members of the hard-hit Orthodox Jewish community have donated.
Consistency is also an issue. The mix and concentration of antibodies differs from one donor to the next, which "is one of the unfortunate reasons why the clinical evidence generated around convalescent plasma has remained rather shallow," says Thomas Kreil, head of pathogen safety at Japanese pharma company Takeda. Together with several partners, Takeda is working to produce a product called hyperimmune globulin, for which the blood of hundreds of recovered patients is pooled and the antibodies concentrated about 10-fold. Hyperimmune globulin has a longer shelf life than plasma, and its higher concentration would allow doctors to give more antibodies to patients without the risk of TACO. An efficacy trial, funded by the U.S. National Institutes of Health, could start this summer
