Convalescent plasma therapy for COVID-19: are there any benefits?

Highlights

• The National Institutes of Health (NIH) recently announced the final results from a study assessing convalescent plasma (CP) therapy in COVID-19 outpatients with early symptoms.
• The results demonstrated no significant benefit of the therapy for COVID-19 patients.
• However, additional clinical studies of COVID-19 convalescent plasma therapy are underway or scheduled in different populations.

During epidemics or pandemics, convalescent plasma (CP) therapy has received plenty of attention. Convalescent plasma therapy was proposed primarily for the neutralisation of pathogens through the administration of antibodies. This has been the case for epidemics including Ebola, Junin virus, as well as COVID-19. Moreover, the therapy seems to have been effectively utilised to treat MERS, SARS, and the 2009 H1N1 pandemic.

Before we delve deep into the impact of convalescent plasma therapy on COVID-19 treatment, let us first understand what it is and how it works.

RELATED READ: COVID-19 booster shot for immunocompromised people: are there any additional risks?

What is convalescent plasma therapy?

Convalescent plasma or CP is a method by which passive immunity can be induced artificially by transferring blood plasma from patients who have recovered from the disease to new patients. The introduction of blood plasma of recovered patients can give the recipient immunity to the disease with the presence of antibodies in the blood plasma.

The concept behind convalescent plasma therapy is that people who have had an infection and recovered from it have antibodies and are immune to the virus. In CP therapy, blood from recovered patients is collected and transferred intravenously (IV) to people who do not have antibodies to the infection and, therefore, can get immunity.

Source: © Nnkolev | Megapixl.com

Convalescent plasma therapy for COVID-19

Convalescent plasma is the blood plasma collected from the COVID-19 patients who have recovered from the disease. Last year, the US Food and Drug Administration (FDA) provided an emergency use authorisation (EUA) for convalescent plasma in COVID-19 patients who are hospitalised.

Like other outbreaks, convalescent plasma was considered for the treatment of COVID-19 with the hope that it could help patients suffering from severe COVID-19 to better fight against the virus, and therefore reduce mortality.

Interest in the use of convalescent plasma for COVID-19 developed during the initial stage of the pandemic. Since then, numerous observational studies have been published with variable outcomes. Some studies suggest the convalescent plasma therapy might be a potential treatment for critical COVID-19 patients highlighting the need of conducting well-designed clinical trials.  

Source: © Skmahenurbegum | Megapixl.com

ALSO READ: COVID-19 development: Australia to vaccinate most adults by the end of the year

NIH study demonstrates no notable benefits of CP for COVID-19

The National Institutes of Health (NIH) has conducted a trial evaluating convalescent plasma in COVID-19 patients. The trial’s primary aim was to establish the safety and efficacy of a single dose of convalescent plasma therapy for inhibiting the progression of COVID-19 from mild to severe.

Last week, on 18 August, the US-based medical research agency disclosed the final results of the Clinical Trial of COVID-19 Convalescent Plasma in Outpatients (C3PO). The findings demonstrated that COVID-19 convalescent plasma therapy did not stop the progression of the disease in a high-risk individual of outpatients when administered within the first week of disease indications. The trial was terminated in February 2021 because of the lack of efficacy based on planned interim analysis.

The C3PO trial was initiated in August 2020 and designed to evaluate whether administering COVID-19 convalescent plasma therapy might also be beneficial for people who were recently infected with SARS-CoV-2. The study included adult outpatients with mild COVID-19 symptoms and in emergency departments.

DO READ: What’s impeding global vaccination drive? Debunking myths about COVID-19 vaccines

Clifton Callaway, MD, PhD, the contact principal investigator for the COVID-19 Convalescent Plasma in Outpatients trial, commented-

However, there is no such conclusive evidence or reason for the unexpected results. The NIH is also funding additional clinical trials to get conclusive data to see if the therapy can help COVID-19 patients recover faster. These patients include persons who are in hospitals as well as recovering at home.

Furthermore, NIH highlighted that some additional studies of COVID-19 convalescent plasma are underway or scheduled in various populations, including-

• The Pass It On trial is an NIH-funded randomised trial using convalescent plasma to treat hospitalised COVID-19 adult patients to see if the therapy help the patients to recover faster.
• The other trials are being conducted in outpatients recovering at home as well as in people having an elevated risk of COVID-19 exposure to discover if the convalescent plasma can prevent COVID-19.

Bottom Line

The results from the NIH study concluded that the convalescent plasma therapy did not prevent the progression of COVID-19 in a high-risk group of outpatients. However, the actual reason for this is not known yet, and researchers are exploring possible explanations, such as the timing of plasma administration, insufficient plasma dose and more. Besides, further studies are ongoing to evaluate the CP therapy, so it might not be the end of the road for the treatment just yet.

DO READ: COVID-19: Which are three worst-hit geographical sub-regions?