IAS Gyan

Daily News Analysis

Not all convalescent plasma may have protective effect

18th September, 2020 Health

Context: Not all plasma from those who have recovered from COVID19 in India may contain enough protective antibodies, says a multi-institutional study led by researchers in the country and the U.S.

About Convalescent plasma therapy:

  • It involves transfusion of the blood plasma of a recovered patient into another patient.
    • Plasma is the matrix on which the blood cells float. It also houses crucial components of immunity known as antibodies.
    • Antibodies are the immediate warriors who fight an invading pathogen – an antigen – to defeat it. Some blood cells function as memory cells so that they can identify and defeat the same enemy if and when it invades again by quickly producing the same antibodies.
  • Convalescent plasma therapy banks on the age-old concept of passive immunity when antibodies for some diseases, such as diphtheria, were developed in horses and injected into humans.
    • Active immunity is what is achieved by introducing an attenuated pathogen (such as the BCG vaccine) into the body to generate an immune response.
  • These antibodies last for two-three weeks and during that time, the person is protected against the invading disease. Activated T cells last for a few weeks if transfused from another person and for a few hours to a few days if transfused from an animal.

When has convalescent plasma therapy been tried before?

  • It has been tried for several diseases, most recently for Ebola.
  • The WHO had issued a detailed guidance document for its use in the wake of the Ebola outbreak, to be used as an “empirical treatment modality”.
  • “While there is no proven treatment available for Ebola virus disease (EVD), whole blood collected from patients in the convalescent phase of infection has been used as an empirical treatment with promising results in a small group of EVD cases.