The principle behind this therapy is to transfuse the plasma of subjects recently recovered from Covid-19, therefore rich in antibodies, into sick subjects to kill the virus. The same principle on which the vaccine is based, but with the antibodies served ready and therefore with immediate effect.
A study on this was recently published in the New England Journal of Medicine (NEJM).


In this study, 228 hospitalized patients were intravenously administered plasma from convalescents with high antibody content, while 105 received placebo. The median time from symptoms onset to the date of admission was 7 days. On the thirtieth day from the date of admission, the two groups showed the same percentage of healed and deceased subjects.

According to the conclusions of this study, this type of therapy is useless, and raises doubts about the usefulness of the vaccine that sees the same antibodies at work: what kind of virus is this, which continues to exert its damage even after being killed by specific antibodies?

The study was conducted on hospitalized patients, on the 7th day from the onset of symptoms. In the graphic above, it can be seen that on the seventh day the viral load is minimal, yet the inflammatory response and the severity of the disease are at their peak.

Siddiqi HK, et al. COVID-19 Illness in Native and Immunosuppressed States: A Clinical-Therapeutic Staging Proposal. J Heart Lung Transplant. 2020 Mar 20. doi: 10.1016/j.healun.2020.03.012

The hyperimmune plasma was administered to patients in whom the virus had already done its job of triggering the lethal inflammatory reaction. A very different result would have been observed if the plasma had been administered at the first symptoms, a week before admission to hospital. Since at the first symptoms it is not foreseeable whether the disease will quickly extinguish or develop into a severe form, hyperimmune plasma should be transfused to all symptomatic infected patients at home, and this is not possible.