Human convalescent serum may be a viable option for treating and preventing COVID-19

Laila Zomorodian, MD and Zachary Elliott, MS2

In a 2005 study from North China evaluating the 2003 SARS outbreak, 87 of 99 SARS patients had developed SARS antibodies by 35–180 days after symptom onset, with a mean titer of 1:61. In a Hong Kong study of 80 SARS patients who deteriorated despite methylprednisolone treatment, a non-standardized dose of convalescent serum was given on hospital day 7-30, based on plasma availability; those treated after day 14 did worse, defining “poor outcome” as discharge after 22 days or death. Further, the 30 patients who were presumably naive to SARS (PCR-positive but seronegative) on admission were more likely to have a “good” outcome after getting convalescent plasma than those who were already seropositive (66.7% vs 20%; P=0.001).

Summarized recently by Casadevall, et al, convalescent serum helped to curb the last century’s outbreaks of polio, measles, mumps, influenza, and even the 1918 H1N1 pandemic. Convalescent serum also demonstrated efficacy in the 2009–2010 H1N1 influenza pandemic, the 2013 Ebola outbreak, and the H5N1 and H7N9 avian flu outbreaks.

COVID-19 data is beginning to emerge. Shen, et al in China reported improvement in five critically-ill COVID-19 patients with ARDS after receiving convalescent plasma derived from donors already recovered from COVID-19.

The FDA is granting permission for investigational use of convalescent plasma in COVID-19 treatment, under single-patient emergency Investigational New Drug Applications (INDs) but this is not extended to prophylactic administration. Additionally, there are important risks to consider with the use of blood products, like transfusion-related acute lung injury (TRALI) in the critically ill, especially in a disease process already characterized by ARDS and cytokine/immune dysregulation.