Convalescent Serum and COVID-19

Compiled by

Shashank Heda, MD., Dallas, Texas.

Question: The serum could actually be a virus as there have been cases (documented of course) were even recovered patients were spreading the virus.

Answer: You raised a very interesting question. I appreciate your raising this. However, kindly get the references.

The convalescent serum has been used for several diseases since 1890 by Behring initial experiment with Diphtheria. Eventually, the convalescent serum has been used bacterial infections, pertussis, measles, Argentine hemorrhagic fever, influenza, chickenpox, infections by cytomegalovirus, parvovirus B19 and, more recently, Middle East respiratory syndrome coronavirus (MERS-CoV), H1N1 and H5N1 avian flu, and severe acute respiratory infections (SARI) viruses. Suffice it to say, it is as older as vaccination.

Keeping with the intent of dispelling myth and provide confidence to the community, I am making every attempt to provide transparency based on the existing scientific research. Below, I am attaching two excerpts along with their references.

Convalescent blood products (CBP), obtained by collecting whole blood or plasma from a patient who has survived a previous infection and developed humoral immunity against the pathogen responsible for the disease in question, are a possible source of specific antibodies of human origin. The transfusion of CBP is able to neutralize the pathogen and eventually leads to its eradication from the blood circulation. Different CBP has been used to achieve artificially acquired passive immunity: (i) convalescent whole blood (CWB), convalescent plasma (CP) or convalescent serum (CS); (ii) pooled human immunoglobulin (Ig) for intravenous or intramuscular administration; (iii) high-titer human Ig; and (iv) polyclonal or monoclonal antibodies.

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Convalescent Plasma:

In the absence of specific antiviral agents and vaccines for COVID-19, clinical trials have been conducted aimed at investigating the efficacy of convalescent plasma in treating COVID-19. A very recently published study by Chinese researchers confirmed the efficacy of convalescent plasma in controlling SARS-CoV-2 (Table 1) (Roback and Guarner, 2020). The report suggested that COVID-19 patients showed signs of improvement approximately 1 week after convalescent plasma transfusion. Another clinical study involved 10 critically ill patients infected with COVID-19 from 3 different hospitals in Wuhan suggested high-titer convalescent plasma transfusion can effectively neutralize SARS-CoV-2, leading to impeded inflammatory responses and improved symptom conditions without severe adverse events. All 10 patients receiving convalescent plasma transfusion showed improvement of clinical outcomes or were cured and discharged from the hospital (Duan et al., 2020). Given the clinical effectiveness of convalescent plasma, the FDA has granted clinical permission for applying convalescent plasma to the treatment of critically ill COVID-19 patients (FDA, 2020).

Convalescent plasma collected from donors who have survived an infectious disease by producing protective antibodies is considered to provide a great degree of protection for recipients affected by the emerging virus (Dodd, 2012). Convalescent plasma has been successfully employed to treat numerous infectious diseases, including the 2003 SARS-CoV-1 epidemic, 2009-2010 H1N1 influenza virus pandemic, and 2012 MERS-CoV epidemic (Dodd, 2012, Hung et al., 2011, Mair-Jenkins et al., 2015), for which modern medicine has no specific effective treatment.