Published: 6th Apr, 2020
The United States’ Food and Drug Administration is developing a new coronavirus drug derived from the blood plasma of people who have recovered from Covid-19. Its approach is based on the idea that antibodies developed by recovered patients might strengthen the immune system of new patients.
Context
The United States’ Food and Drug Administration is developing a new coronavirus drug derived from the blood plasma of people who have recovered from Covid-19. Its approach is based on the idea that antibodies developed by recovered patients might strengthen the immune system of new patients.
About
- The idea of using plasma from survivors, also known as convalescent-plasma therapy, dates back to the late 19th century.
- The treatment was first used in the 1890s and helped stem a number of outbreaks until antimicrobial therapy, which kills or halts the microorganism, was developed in the 1940s.
- In the early 20th century, convalescent plasma treatment was used during outbreaks of diseases such as measles, mumps and influenza.
- More recently, it was used during the H1N1 influenza pandemic, and again in 2013 during the Ebola outbreak in West Africa. In the case of the latter, two patients survived the disease after treatment.
- Following the Ebola outbreak, the World Health Organization issued guidance for its use in treating the disease, saying the small group it was used on showed "promising results."
- Doctors have transfused the blood of recovered patients into those still sick with the 1918 flu, measles, polio, chickenpox and SARS —to varying degrees of success.
How is blood plasma turned into an infection-fighting drug?
- Patients who have recovered from a disease have permanent antibodies generated by the immune system floating in their blood plasma, the liquid component of blood.
- To turn that into a drug, the plasma is harvested, tested for safety, and purified to isolate those protective antibodies.
- When injected into a new patient, the “plasma-derived therapy” — also known as convalescent plasma — provides “passive immunity” until the patient’s immune system can generate its own antibodies.
Challenges:
- Despite the potential utility of passive antibody treatments, there have been few concerted efforts to use them as initial therapies against emerging and pandemic infectious threats.
- The absence of large trials certainly contributes to the hesitancy to employ this treatment.
- Also, the most effective formulations (convalescent plasma or hyperimmune globulin, H-Ig) are unknown.
- Convalescent plasma has the advantage that while its antibodies limit viral replication, other plasma components can also exert beneficial effects such as replenishing coagulation factors when given to patients with hemorrhagic fevers such as Ebola.
- On the other hand, individual convalescent plasma units demonstrate donor-dependent variability in antibody specificities and titers. H-Ig preparations, in contrast, contain standardized antibody doses, although fractionation removes IgM, which may be necessary against some viruses.
- Nonetheless, the construction of a strategic stockpile of frozen, pathogen-reduced plasma, collected from Ebola-convalescent patients with well-characterized viral neutralization activities, is one example of how to proceed despite existing unknowns.
Conclusion:
Convalescent plasma is a “very important area to pursue” as a potential treatment for patients with Covid-19. This must be given at the right time because it mops up the virus in the system and gives the new patient’s immune system a vital push at the time it needs it.
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