COVID-19: Natural immune response may pave way for treatment

As COVID-19 continues to ravage the world, scientists are racing against the clock to find a way to treat and contain it.

A number of laboratories are currently developing vaccines as well as testing new and re-purposed drugs (i.e. existing drugs that may treat a different disease). Yet the oldest treatment being tested is convalescent plasma.

What is plasma?

Plasma is the largest component of our blood. It carries nutrients, hormones and proteins to the organs that require them and helps remove waste from the body.  Plasma is also a critical part of treatment for many serious health problems as antibodies are mainly produced by plasma cells. This is our bodies’ natural response to a disease.

2019 COVID - Passive antibody therapy treatment  

How does the treatment work?

Recovered patients’ plasma contains antibodies that may help those whose systems are struggling to develop their own. Plasma collected from patients who recovered from the novel coronavirus is transfused into those battling the disease, providing protection against it. This treatment is also called passive antibody therapy, as it is a type of passive immunity.

Antibodies already produced by the recovered patients

How is it different from a vaccine?

Vaccines stimulate antibody production to infection you have not yet had. Meaning that when you get a vaccine, you body will create a vaccine-induced immunity. You will then build resistance to a disease without having it.

Natural immunity, on the other hand, is what happens when your body builds resistance to a disease after getting it and recovering on its own. This is where plasma treatment comes in, as it relies on the antibodies already produced by the recovered patients.

Vaccines also take a long time to be tested and approved. Plasma treatment is considered to be relatively safe.

Has it been used before?

Clinical trials of plasma treatment 

Convalescent plasma was previously used to help stop outbreaks of mumps and measles before vaccines were available.  There is also some evidence that those who got plasma during the 1918 influenza pandemic were less likely to die. More recently, the treatment was used during SARS and Ebola outbreaks in 2003 and 2013-2016 respectively.  However, large trials have never been carried out and evidence on exactly how it works is insufficient.

But the Coronavirus has changed that. Despite its long history, never before has the use of plasma been tested at such large scale. In the absence of a vaccine, multiple clinical trials are taking place in the UK, Italy, Russia and the US.

Whatever the outcome, we will finally be able to see if this treatment is viable. And the solution, or at least part of it, may well be in our natural immune response to this virus. Fingers crossed.

Sources: Nature  URMC  NHSBT  The Conversation

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