The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), popularly known as COVID-19, has spread like a wildfire and with several nations still struggling with bending the infection curve, it is a race against time to come up with effective pharmaceutical approaches. As of now, several trials for repurposed drugs like Remdesivir and Favipiravir are currently underway against COVID-19 but the anti-viral efficacy of these drugs has not yet reached any adequate or conclusive end. Although COVID-19 research is advancing at a rapid speed with detection kits, vaccines, and alternative medicine, clinicians are quite heavily leaning on an old way of treatment called Convalescent Plasma Therapy, based on siphoning blood plasma from COVID-19 survivors and infusing it into patients. Lately, the Indian Council of Medical Research has also announced the initiative of pursuing COVID-19 human trials in Delhi using this survivor-plasma infusion procedure. But why are researchers and clinicians going after plasma therapy instead of chasing innovative drug lead ideas? Let us see.
What is Convalescent Plasma Therapy?
Passive immunization and artificially acquired passive immunity date back to the 20th century for the treatment of infectious diseases. A short-term immunization against infectious agents can be achieved by infusion of blood plasma containing pathogen-specific antibodies in the patient’s blood. Although bacterial infections can be well treated using antibiotics, passive immunization using this concept of convalescent plasma therapy remains an important tool against viral infections as the bridge between complications and effective clinical drug treatment.
In Convalescent Plasma Therapy, blood plasma is obtained from a recovered patient who has developed a humoral immunity (antibody-based immunity) against a particular pathogenic infection. The transfusion of this blood plasma in patients suffering from that particular infection helps in neutralizing the pathogen by being a potential source of anti-pathogen antibodies and rejuvenating platelets.
Why is Convalescent Plasma Therapy considered for COVID-19 treatment?
The plasma therapy has been used against serious epidemic infections, prior to COVID-19, and has always proven to be effective for sustenance till the approval of specific drug candidates. Going back, in 2009, convalescent plasma was found to show improvement in patients affected by the H1N1 pandemic. In 2014, the World Health Organization recommended the use of convalescent plasma collected from Ebola survivors as empirical treatment. During MERS-CoV in 2015, a similar concept of plasma therapy was practiced. In every situation, convalescent plasma therapy was found to reduce the viral load and mortality without any severe side effects. Therefore, when drugs and vaccines were not living up to the time expectations against COVID-19, researchers went ahead with trying out Convalescent Plasma Therapy. Recent clinical evidence shows that convalescent plasma from COVID-19 survivor patients can be effectively used as a treatment against this new coronavirus disease. Therefore, FDA has currently issued some guidelines to regulate and encourage healthcare providers and researchers to study the efficacy and mechanism of Convalescent Plasma Therapy in COVID-19 patients. Based on these guidelines, randomized clinical trials are already being pursued.
Any Issues with Convalescent Plasma Therapy?
The identification, selection, and recruitment of potential COVID survivors (donors) can be a cumbersome task and is a major difficulty as convalescent survivors must meet donor selection criteria complying with national policies and routines. But due to the extremity of COVID-19 mayhem, WHO has suggested to relax some donor criteria with the intention of speeding up the treatment in optimal safety.