WHAT IS CONVALESCENT PLASMA THERAPY?
The convalescent plasma therapy aims at using antibodies from the blood of a recovered Covid-19 patient to treat those critically affected by the virus. The therapy can also be used to immunize those at a high risk of contracting the virus — such as health workers, families of patients, and other high-risk contacts.
This therapy’s concept is simple and is based on the premise that the blood of a patient who has recovered from Covid-19 contains antibodies with the specific ability to fight novel coronavirus. The theory is that the recovered patient’s antibodies, once ingested into somebody under treatment, will begin targetting and fighting the novel coronavirus in the second patient.
The convalescent plasma therapy is akin to passive immunization as, according to researchers, it is a preventive measure and not a treatment for the Covid-19 disease.
HOW CONVALESCENT PLASMA THERAPY WORKS?
The convalescent plasma therapy uses antibodies developed within an infected person while he/she is infected with the novel coronavirus.
These antibodies are developed in a patient as part of the body’s natural immune response to a foreign pathogen or in this case, the novel coronavirus. These antibodies are highly specific to the invading pathogen and so, work to eliminate the novel coronavirus from the patient’s body.
Once the patient has recovered, they donate their blood so that their antibodies can be used to treat other patients. The donated blood is then checked for the presence of any other disease-causing agents such as Hepatitis B, Hepatitis C, HIV, etc.
If deemed safe, the blood is then taken through a process to extract ‘plasma’, the liquid part of the blood that contains antibodies. The antibody-rich plasma, once extracted, is then ingested into the body of a patient under treatment.
WHAT ARE RISKS INVOLVED?
Besides speaking about the success of the convalescent plasma therapy, the study by John Hopkins immunologists stated some of the risks associated with it:
- Transfer of blood substances: As the blood transfusion takes place, there are risks that an inadvertent infection might get transferred to the patient.
- Enhancement of infection: The therapy might fail for some patients and can result in an enhanced form of the infection.
- Effect on the immune system: The antibody administration may end up suppressing the body’s natural immune response, leaving a Covid-19 patient vulnerable to subsequent re-infection.
WHERE ELSE IS PLASMA THERAPY USED?
This is not the first time convalescent plasma therapy is being considered as a treatment for viral infections.
- In 2014, the World Health Organisation (WHO) had recommended the use of convalescent plasma therapy to treat patients with the antibody-rich plasma of those who had recovered from the Ebola virus disease.
- For the treatment of people infected with the Middle East respiratory syndrome (MERS), which is also caused by a coronavirus, a protocol for use of convalescent plasma was established in 2015.
- During the 1918 H1N1 influenza virus (Spanish flu) pandemic, the therapy was used experimentally.
- The plasma therapy was used as a treatment during the H1N1 infection of 2009.
Other serious outbreaks that have seen the use of this therapy are the SARS outbreak, Measles, HIV, polio, and mumps.
PLASMA THERAPY AND COVID-19
Plasma therapy’s potential as a treatment for Covid-19 has already been explored in limited trials in China, where the outbreak first emerged. In one trial, 10 critically-ill Covid-19 patients were subject to convalescent plasma therapy. The trial showed some improvement in the patients’ condition.
“No severe adverse effects were observed. This study showed CP [convalescent plasma] therapy was well tolerated and could potentially improve the clinical outcomes through neutralizing viremia [the presence of viruses in the blood] in severe Covid-19 cases,” the researchers who conducted the trial said.
Another trial conducted by researchers in Shenzhen, China treated five critically-ill Covid-19 patients with plasma therapy and found “improvement in [they are] clinical status”.