DH Deciphers | Can plasma therapy really cure COVID-19 or is it yet another trial?

Convalescent plasma therapy is the new buzzword in the fight against the novel coronavirus. Scores of people who have recovered from coronavirus have donated their plasma to help patients still battling the disease.

At least one patient is reported to have been cured of infection after getting plasma transfusion at a private hospital in Delhi. Many states are clamouring to get the Indian Council of Medical Research's (ICMR) approval to conduct clinical trials of plasma therapy. But does convalescent plasma therapy really work? Read on to find out.

What is convalescent plasma?

Plasma is the pale yellow liquid that forms 55% of human blood. The other 45% consists of red blood cells, white blood cells and platelets. Convalescent plasma is the plasma removed from the blood of a patient who has recovered from a disease (convalesce means to take rest to get better after an illness).

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Your body produces antibodies when it's exposed to foreign pathogens, such as viruses or bacteria. An antibody is a protein produced in the blood that clings to the virus, helps deactivate it, clears it from circulation and prevents it from invading the body's cells. So the plasma donated by a cured patient is rich in antibodies. And this antibody-rich plasma can fight the virus in other people. When it is transfused into existing patients, it may boost their immune system, giving them a better chance of fighting the disease.

Convalescent plasma can last up to a month, and up to a year when it's frozen. A person can donate about 500 ml of convalescent plasma that can help two patients.

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If there's no cure or vaccine for COVID-19, how can we trust plasma therapy?

It's true that there's no cure or vaccine for COVID-19 but researchers in 55 clinical trials registered across the globe are assessing the use of convalescent plasma to treat the infection.

Three of these trials are in the first phase (when the treatment is tested on a small number of people). One such trial is going on in Bengaluru. There is, however, anecdotal evidence that plasma therapy could well be working. And that gives us hope.

Can every cured patient donate plasma?

No. A patient cured of COVID-19 can donate plasma only if he or she was symptom-free for 28 days before donation. In the case of asymptomatic coronavirus patients, this period is 14 days. Besides, the cured patient should not have any other transmittable disease.

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I tested positive for coronavirus and have mild symptoms. Can I go for plasma therapy?

Not so fast. The most important criterion for receiving plasma therapy is criticality, says Dr Vishal Rao, principal investigator of the clinical trial for plasma therapy at HCG Hospital in Bengaluru. Only patients who are on ventilators or are critical are eligible. In short, you have to be battling for your life to get plasma therapy. Pregnant or lactating women aren't eligible either.

What's the donation process?

Donating the plasma is similar to blood donation but there are some differences. The process takes between 90 minutes and two-and-a-half hours.

In a blood donation, the blood is drawn into a bag that's connected to a hose which is, in turn, attached to the needle. In a plasma donation, the donor's blood is drawn into a centrifuge (machine) where the plasma is separated from other components and collected in a separate bag. The remaining blood is injected back into the donor's body.

What's the scene in Karnataka?

Out of 520 patients in the state, at least 193 have recovered. Fifty-seven of them are in Bengaluru and 43 in Mysuru. The challenge is to get in touch with these patients and convince them to donate their plasma. Authorities have already made a public appeal to all the cured patients in this regard.