What is convalescent plasma?

• People who have recovered from COVID-19 have antibodies to the disease in their blood. Doctors call this convalescent plasma.
• Researchers hope that convalescent plasma can be given to people with severe COVID-19 to boost their ability to fight the virus.
• Everyone who has suffered from a disease possibly carries what are called neutralising antibodies that when extracted via plasma and transfused on to others with the infection can help their immune system fight it off.

What are antibodies?

• Antibody, also called immunoglobulin, is a protective protein produced by the immune system in response to the presence of a foreign substance, called an antigen.
• Antibodies recognize and latch onto antigens in order to remove them from the body.
• A wide range of substances are regarded by the body as antigens, including disease-causing organisms and toxic materials such as insect venom.

What are the challenges?

• For all these studies to get off the ground, researchers would need enough donors who have recovered fully and can be tested for other pathogens as well.
• People should be willing to donate plasma, and good tests should emerge to estimate how many antibodies they have.
• While studies are required to show the timing and dosage, there is broad consensus that early administration will be ideal.

Why is timing crucial?

• Early on in the disease, there is a lot of virus in the system and the antibodies will bind with the virus eliminating it.
• If this is not done at this stage, then the virus sets off a cascade of inflammation in the body.
• If the patient has reached that stage, the plasma may not be helpful.

Need for blood donation

• Since it rests on blood donation, people from the more common blood groups, for instance, O+ve, will have easier access to plasma.
• Naturally, the pool for rare blood groups is going to be smaller.
• However, experts have been laying emphasis on the need for people who have recovered to voluntarily come forward and donate plasma to help with research and other patients.

Earlier trials

• This is not the first time that plasma from recovered patients has been used to treat people infected with certain viruses for which drugs are not available.
• When Ebola struck Guinea, Sierra Leone, and Liberia in 2014, the World Health Organization prioritised the evaluation of treatment with convalescent plasma derived from patients who have recovered from the disease.
• Treatment with convalescent plasma is a classical, time-tested method. It has been used against measles, chickenpox, and rabies.

Why in the news ?

• A team of scientists from the Scripps Research Institute in the U.S. has discovered that neutralising antibodies present in the blood of COVID-19 infected who have recovered offers powerful protection against novel coronavirus in animals.
• The researchers found that passive transfer of neutralising antibodies into Syrian hamsters protects them against the disease when exposed to the virus.