While scientists around the world work toward a COVID-19 vaccine, convalescent plasma therapy may offer hope to those stricken with the disease.

With a vaccine against COVID-19 still many months away, scientists are looking to the blood of those who have recovered from the disease to develop a treatment. Evocative of vampiric imagery as it may be, this strategy is rooted in a medical treatment proven to be effective over a century of use.

The approach is to transfuse convalescent plasma, or antibody-rich plasma of recovered patients, into COVID-19 patients with active infections. The hope is these antibodies can help those patients to fight off the disease. 

Detection of a virus kickstarts an individual’s immune system, stimulating it to fight infection. Antibodies to a virus are produced as part of this response, each functioning like a targeted, virus-eating Pac-Man, helping to reduce disease progression. When it works well, those suffering from mild COVID-19 can heal without any special medical intervention, save for over-the-counter medication such as acetaminophen for fever. 

For patients battling more severe infections, such as those in respiratory distress requiring oxygen or ventilator support, the immunity boost afforded by convalescent plasma transfusion could mean the difference between death and survival.

Introducing the antibodies of recovered patients to those severely ill would be like giving them the temporary use of an additional, borrowed immune system - a supplemental defence to aid their own. With fewer viral particles present to continue wreaking havoc, symptoms would be reduced and the patient put on a quicker road to an otherwise uncertain recovery. 

While there is no guarantee that convalescent plasma therapy will be successful for treating COVID-19, it has worked in the past to treat the Spanish flu and, more recently, SARS and Ebola. 

Clinical studies of convalescent plasma therapy for COVID-19 are currently underway around the globe. A recent study out of China, the first global epicentre of the disease, reported a reduction in viral load, or the amount of viral particles in a patients’ systems, after treatment. The result was the recovery of five critically ill patients, giving scientists reason beyond mere hope to continue to pursue this therapeutic strategy for COVID-19.

Still, other aspects affecting the success of plasma therapy remain undetermined. The ideal range of days after a patient’s recovery during which to collect blood, as well as the dose, timing, and tolerability of treatment have yet to be fully teased out by scientists. 

Another consideration is the quantity of convalescent plasma available for use as a treatment, and how it would be distributed. Should convalescent plasma therapy prove effective for COVID-19, supply of donated plasma would be limited, as only those infected and recovered could be donors. One recovered individual can provide enough plasma for two to four transfusion doses, with current dosing recommendations set at one per patient. 

Therapy would be considered first for those severely ill with COVID-19 and suffering the kinds of symptoms that could prove fatal. Only once the most critically afflicted have been served could treatment be extended to prevent those more mildly sick from declining further into illness. Ultimately, the treatment could be offered to the elderly, immunocompromised and otherwise at-risk members of the public to boost immunity before a vaccine becomes available. 

With every passing day, newly reported infections and deaths remind us that the search for a therapy that can be administered now is of critical importance. An alarming number of people remain infected, and many more will fall ill before the pandemic begins to abate. 

The few recoveries attributed to convalescent plasma therapy remind us that wherein lies promise, lies hope. Despite the tragic loss of thousands that have died from this disease, there are many thousands more who have recovered. The antibodies they carry within them offer strength to aid global recovery. 

Reinstating the normalcy we once knew is out of the question until we can all be armed with the protection that a vaccine affords. While we wait, those of us who have recovered may offer ourselves, in this time of crisis, to help in our shared cause. 

Resources:

https://nationalpost.com/news/canada/researchers-to-study-whether-plasma-of-recovered-patients-can-treat-covid-19

https://www.cnbc.com/2020/04/07/mayo-clinic-ceo-says-convalescent-plasma-could-be-effective-treatment-for-coronavirus.html

https://www.pnas.org/content/early/2020/04/02/2004168117

https://www.kiro7.com/news/trending/coronavirus-what-is-convalescent-plasma-therapy-can-it-protect-you-covid-19/44DVCZ2RL5BZRLHJFNIZBQUJ3I/

https://www.cnn.com/2020/03/25/health/coronavirus-blood-plasma-treatment-fda/index.html

https://www.statnews.com/2020/03/05/how-blood-plasma-from-recovered-patients-could-help-treat-coronavirus/

https://hub.jhu.edu/2020/04/08/arturo-casadevall-blood-sera-profile/

https://www.contagionlive.com/news/new-life-for-an-old-therapy-convalescent-plasma

https://www.theverge.com/2020/4/13/21216513/plasma-blood-coronavirus-treament-drug-development-antibodies

By: Natalie Workewych

Natalie is a PhD Student studying Pharmacology at the University of Toronto. Her academic background includes an undergraduate degree in Biochemistry and Pharmacology. She hopes to encourage ideas through writing, and bring thoughts on science to anyone the least bit curious.