Uncertain outcome, high cost: Why WHO doesn’t recommend convalescent plasma therapy for COVID-19

Studies published in late 2020 and early 2021 made a case for plasma therapy in treating COVID-19

By Taran Deol
Published: Tuesday 07 December 2021

The World Health Organization (WHO) has recommended December 6, 2021 against the use of convalescent plasma therapy for novel coronavirus disease (COVID-19) treatment. High uncertainty of outcome, logistical concerns were some of the factors cited by the United Nations health agency.  

“Despite its initial promise, current evidence shows that it does not improve survival nor reduce the need for mechanical ventilation, and it is costly and time-consuming to administer,” WHO noted.

There was sufficient uncertainty in patients with severe and critical illness to warrant continuation of randomised controlled trials, the organisation said. The recommendation was based on findings from 16 trials involving 16,236 patients with non-severe, severe and critical infections. 

WHO also listed several logistical concerns surrounding this line of treatment. The process of identifying and testing potential donors, collecting, storing and administering plasma therapy is not entirely practical and causes feasibility issues, according to the agency.

The guidance adds to a list of previous recommendations on: 

  • Use of interleukin-6 receptor blockers and systemic corticosteroids for patients with severe or critical COVID-19
  • Use of neutralising monoclonal antibodies in selected patients
  • Use of ivermectin and hydroxychloroquine in patients with COVID-19 regardless of disease severity

The treatment uses blood from those who have recovered from COVID-19 since they have antibodies from natural infection. Antibodies and plasma — a clear liquid — are separated from blood cells and introduced into the patient’s body. 

Studies published in late 2020 and early 2021 had made a case for plasma therapy in treating COVID-19. Peer-reviewed articles published later, however, did not find similar benefits. Among them was a study done in India.

Earlier this year, the All India Institute of Medical Sciences-Indian Council of Medical Research COVID-19 National Task Force and the Union health ministry decided to drop the treatment.

Convalescent plasma therapy “did not lead to reduction in progression to severe COVID-19 or all-cause mortality, according to a November 2020 study by ICMR. The study included 464 “moderately ill” patients. 

The therapy should not be administered unless advised by ICMR under specific circumstances, the report noted. 

These include: 

  • If the recipient is in early stages  (three-seven days and not more than 10 days since the onset of symptoms) of the COVID-19 infection 
  • The patient has no antibodies against COVID-19 
  • Informed consent of the patient 

For the donor, there are several criteria including a positive test, 14 days since the resolution of symptoms and a required concentration of antibodies. 

In May 2021, two days after a Lancet report echoed ICMR’s concerns, India’s health ministry  advised against plasma therapy for treating COVID-19. The study by Randomised Evaluation of COVID-19 Therapy was done on 5,795 patients who received the treatment and 5,763 who didn’t in a “randomised open-label study” across 177 hospitals in the United Kingdom. 

There was no evidence that convalescent plasma provided any benefits over and above usual care, the analysis showed. “Additionally, no significant effect was observed on the proportion of patients discharged from hospital within 28 days.” 

Data for the study was collected between May 2020 and January 2021, underlining that the delta variant did not impact the outcome. 

Special populations, such as patients with impaired humoral immunity, who were not actively considered in this study, might still benefit from convalescent plasma therapy, scientists noted in the report. 

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