The World Health Organization now strongly recommends against the use of convalescent plasma in the treatment of COVID-19 patients regardless of their stage of illness. This recommendation, announced in an updated guideline today (December 6), is based on multiple clinical trials that involved more than 16,000 patients.

Convalescent plasma is plasma from patients who have recovered from COVID-19, which includes any SARS-CoV-2–neutralizing antibodies they are producing. It was proposed that infusing such plasma into people with current infections could alleviate symptoms. In March 2020, the FDA allowed researchers to request authorization to use this plasma therapy under an emergency investigational new drug protocol for patients critically ill with the disease, despite the lack of data from clinical trials.

In August of last year, the FDA granted emergency use for convalescent plasma use as a treatment for COVID-19 amid skepticism from many experts. At the time, National Institutes of Health (NIH) Director Francis Collins and National Institute of Allergy and Infectious Diseases (NIAID) Director Anthony Fauci both called for further study and for the FDA to reconsider its announcement, pointing to weak results from a large clinical trial by the Mayo Clinic.

See “Doctors Forge Ahead with Plasma for COVID-19, Benefits Uncertain

In September 2020, randomized clinical trials in India found the treatment neither slowed progression of the disease nor improved survival. More data on convalescent plasma slowly trickled in, but none of it convincingly supported the treatment. In February 2021, the NIH halted a clinical trial involving hundreds of patients after an independent advisory panel found no clear benefit for slowing the disease or preventing death. The monitoring board concluded that the treatment is safe, but not more effective than a placebo. 

According to a WHO press release about the updated recommendation, international experts who panel the WHO Guideline Development Group believe the drug’s use in treating COVID-19 is simply “not justified.” Not only is the treatment expensive and time-consuming to administer, but challenges remain with regards to identifying and testing plasma donors as well as collecting and storing the plasma. Therefore, although the drug itself does not appear to cause harm, the WHO recommends against its use.

The WHO statement notes one exception: it states that there is “sufficient uncertainty” as to the efficacy of convalescent plasma in severely ill patients, and thus the agency favors continuing randomized controlled trials in that group.